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319 Cards in this Set
- Front
- Back
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T/F. All adaptive immune responses entail the production of antibodies.
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F
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The myeloid progenitor is the precursor of which cells?
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granulocytes, macrophages, dendritic cells, mast cells
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Which cells are chiefly important in defense against parasitic infections?
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eosinophils
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The common lymphoid progenitor gives rise to what cells?
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lymphocytes and NK cells (also dendritic cells)
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The central or primary lymphoid organs include what?
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bone marrow and thymus
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(B/T) cells are more lateral in the lymph node.
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B; T cells are located in the paracortical area (more medial)
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The red pulp of the spleen is responsible for what?
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red cell disposal
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Which cells of the immune system are active in innate immunity?
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macrophages and neutrophils
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What is the difference between cytokines and chemokines?
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Cytokines – affect behavior of other cells; chemokines – attract cells
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(Neutrophils/macrophages) respond to inflammation first.
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neutrophils
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Dendritic cells present the material that they ingest to what?
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T lymphocytes
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T/F. The variable region of an antibody consists only of light chain.
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F. both heavy and light
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T/F. Both the B and T lymphocytes generate Ig that have two antigen-recognition sites.
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F. T has only 1 antigen recognition site
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T/F. Both B and T lymphocytes receive co-stimmulatory molecules from dendritic cells.
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F. T cells do, but naïve B cells get it from effector T cell
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T/F. Activated dendritic cells are the only APC.
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F. macrophages and B cells presenting foreign antigen on their surface
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In general, (B/T) cells reognize bacteria and (B/T) cells recognize viruses.
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B – bacteria (outside cells); T – viruses (inside cells)
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Humoral immunity refers to what?
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antibodies
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How do antibodies deal with extracellular pathogens?
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neutralization, opsonization, complement
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(B/T) cells are responsible for cell-mediated immune responses of adaptive immunity.
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T
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Cytotoxic T cells express CD ___ on their cell surfaces.
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CD8
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T Helper cells express CD ___ on their cell surfaces.
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CD4
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Th1 cells express CD ___ on their cell surfaces and do what?
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CD4; activate macrophages to induce fusion of lysosomes with vesicles containing the bacteria; release cytokines and chemokines that attract macrophages; activate B cells
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`
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CD4; stimulate B cells
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MHC class I molecules collect peptides derived from proteins synthesized where? MHC class II?
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class I – cytosol; class 2 – intracellular vesicles
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Which MHC class presents viral proteins on the cell surface?
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MHC class I
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MHC class I is recognized by which class of T cell?
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CD8 (cytotoxic); class I – viruses
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MHC class II is recognized by which class of T cell?
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CD4
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(Macrophages/neutrophils) are the first to encounter pathogens.
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macrophages; then recruit large numbers of neutrophils
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What are 3 toxic products macrophages and neutrophils generate to kill engulfed microorganisms?
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nitric oxide, superoxide anion, hydrogen peroxide
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(Macrophages/neutrophils/both/neither) are long-lived.
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macrophages
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Chronic granulomatous disease patients have a genetic deficiency of what?
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NADPH oxidase
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How do mycobacteria evade destruction?
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grow inside macrophage phagosomes by inhibit acidification and fusion with lysosomes
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Inflammatory responses, such as increase in vascular diameter and expression of adhesion molecules, are mediated by (macrophages/neutrophils/both).
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macrophages
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Which complement factor is a chemoattractant for neutrophils and monocytes and activates phagocytes and local mast cells
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C5a
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Kinin and bradykinin do what?
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increase vascular permeability
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What is unique about bacterial DNA that allows the immune system to recognize it?
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unmethylated repeats of dinucleotide CpG
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What is unique about viral nucleic acids that allows the immune system to recognize it?
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double stranded RNA
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Pattern recognition receptors recognize what (examples)?
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CpG, double stranded RNA
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TLR-4 signals the presence of what?
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LPS on bacteria
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TLR in general recognize what?
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molecular patterns that are not found in normal vertebrates
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Which bacteria have LPS?
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gram-
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What are the three pathways that complement can be activated?
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classical (direct, CRP, antigen-antibody); mannose-binding lectin; alternative (pathogen surfaces
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The classical pathway involves which complement factor?
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C1q
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The alternative pathway involves which complement factor?
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C3
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The three pathways of complement activation converge on which protease?
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C3 convertase
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In the context of complement, the smaller cleage fragment is designated as (a/b).
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a (remember: b – Big)
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Which complement activation pathway can act as an amplification loop?
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alternative b/c it is initiated by the binding of C3b
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Which complement activation pathway has a role in both innate and adaptive immunity?
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classical pathway (but can act in the absence of adaptive immunity, too)
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How is the alternative pathway initiated?
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spontaneous hydrolysis of C3
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T/F. C6, 7, 8, and 9 are involved in inflammation, opsonization, and the assembly of the membrane-attack complex.
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F. only assembly of the membrane attack complex
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How is the activation of C1 prevented?
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serpin (serine protease inhibitor)
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What is the inheritance pattern of paroxysmal nocturnal hemoglobinuria, and what does it involve?
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X-linked; problem with CD59 and DAF (decay accelerating factor); problem with complement-mediated destruction of RBCs
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T/F. Cytokines are a subset of chemokines.
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F. other way around
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What is the difference between CC chemokines and CXC chemokines?
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CC – 2 adjacent cysteines near the amino terminus; CXC – 2 cysteines separated by a single AA
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Weibel-Palade bodies in the endothelial cells contain what?
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preformed P-selectin
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(Selectins/ICAMs) act first in the recruitment of leukocytes.
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Selectins
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(P/E/L) selectin first appears on endothelial cells following inflammation.
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P, then E a few hours later
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CXCL8 is released by _____ and recruits _____.
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released by macrophages; recruits neutrophils
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CCL2 recruits what?
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monocytes
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TNF-alpha does what?
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vasodilation; disseminated intravascular coagulation
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Which factors are responsible for increasing body temperature?
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TNF-alpha, IL1-beta; IL-6
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T/F. Interferon-alpha, beta, and gamma are induced by viral infection.
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F. alpha and beta are, but gamma is produced later
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Interferon synthesis occurs in response to what?
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Double-stranded RNA
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How do interferons inhibit viral replication
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degrade viral RNA; inhibit protein synthesis; increase MHC class I molecules
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T/F. NK cells develop from the common myeloid progenitor cell.
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F. common lymphoid progenitor cell
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What activates NK cells?
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Interferon-alpha, beta, or IL-12
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NK cells kill other cells bearing low levels of what?
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MHC class I molecules
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T/F. Like alpha:beta T cells, gamma:delta T cells recognize antigen as peptides presented by MHC molecules.
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F. recognize antigens directly
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T/F. B and T cells are involved with a adaptive immunity only.
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F. intraepithelial gamma:delta T cells and B-1 cells and NK T cells
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T/F. T cell receptors recognize antigen directly.
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F. recognize antigen bound to MHC molecules on the surfaces of other cells
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IgG antibodies consist of __ heavy and __ light chains. The heavy chains are linked together by ___. The light chains are linked to heavy chains by ___.
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2 heavy, 2 light; heavy to light by disulfide bond; heavy to heavy by disulfide bond
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What are types of light chains?
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lambda and kappa (kappa twice as frequent as lambda)
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What class of Ig is most abundant?
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G
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T/F. The light chain has a constant region.
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T
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An antibody cleaved by papin results in what?
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two antigen-binding fragments (Fab); one Fc (Fragment crystallizable) domain
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An antibody cleaved by pepsin results in what?
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F(ab')2 fragment (2 antigen-binding arms remain linked)
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What are haptens?
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small molecules; recognized by antibody but able to stimulate anti-hapten antibodies only when linked to larger protein carrier
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There are ___ hypervariable regions in both the heavy and light chains.
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3: HV1, HV2, HV3
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Combinatorial diversity in the context of Ig refers to what?
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different combinations of heavy and light chain V regions & genes encoding V regions created from smaller segments of DNA
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What is an epitope?
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structure recognized by an antibody
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T/F. T cells interact with pathogens and their toxic products in the extracellular spaces of the body.
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F. Immunoglobulins do; T cells recognize foreign antigens that are displayed on the surfaces of the body's own cells
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What does the T cell receptor consist of?
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T cell receptor alpha and beta chains linked by a disulfide bond (minority are gamma-delta)
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T/F. T cells respond to discontinuous amino acid sequences in proteins.
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F. short contiguous sequences
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MHC class (I/II) present peptides from viruses.
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class I
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MHC class II are normally found on what?
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B lymphocytes, dendritic cells, and macrophages and not on other tissue cells
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When CD4 T cells recognize peptides bound to MHC class II molecules on B cells, what happens?
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stimulate B cells to produce antibody
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When CD4 T cells recognize peptides bound to MHC class II molecules on macrophages, what happens?
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activate these cells to destroy pathogens in their vesicles
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The ends of the peptide-binding cleft are more open in MHC class (I/II) molecules.
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more open in MHC class II molecules
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MHC class I molecules bind what?
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short peptides of 8-10 AA by both ends
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T/F. The length of peptides bound by MHC class II molecules is constrained to 8-10 AA's.
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F. not constrained; at least 13 Aas (typically 13-17 Aas)
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T/F. Somatic hypermutation occurs in both B and T cells.
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F. B cells only
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T/F. The light chain contains V, D, and J.
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F. only V and J
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What is the order of joining V, D, and J for the heavy chain?
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DJ is present before V comes
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T/F. The heavy chain contains V, D, and J.
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T
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Kappa and lambda in the context of Ig refer to what?
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types of light chain
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What does the recombination signal sequence consist of?
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heptamer, spacer, and nonamer
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What is the 12/23 rule?
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gene segment flanked by an recombination signal sequence with a 12-bp spacer can be joined only to one flanked by a 23-bp spacer RSS
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What prevents V segments from joining to each other?
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The 12/23 rule
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Which enzymes are involved in VDJ recombination?
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RAG 1 and 2
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What are sources of diversity in V regions?
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combinatorial diversity; junctional diversity (addition and subtraction of nucleotides); combinations of heavy and light (also called combinatorial); somatic hypermutation
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(Heavy/light) chain gene arrangement occurs first.
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heavy
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There are 3 hypervariable loops in the protein chains of immunoglobins. Where are they with respect to V, D, and J?
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2 are in V region; 1 in D (for heavy chain); between V and J for light chain
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What is the difference between P and N nucleotides in the context of junctions between gene segments?
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P – palindromic; N – nontemplate-encoded
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When does somatic hypermutation occur?
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when B cells respond to antigen along with signals from activated T cells
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T-cell receptor gene rearrangement takes place where?
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thymus
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T/F. The T cell receptors alpha and beta contain V, D, and J.
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only beta does; alpha contains only v and j
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T/F. CDRs 1, 2, and 3 of TCRs contact the peptide bound in the MHC.
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F. only CDR3
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T/F. T cells undergo somatic hypermutation.
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F. only B cells do
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naïve B cells have ig (M, D, G, E, A) on their surface.
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both M and D
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What is the difference in structure between a secreted and a membrane-bound form of immunoglobulin?
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Membrane-bound form, the Ig heavy chain has a hydrophobic transmembrane domain of 25 AA at the carboxy terminus
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Which Ig forms pentamers in serum?
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IgM
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Which Ig can occur as either a monomer or a dimer?
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IgA
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T/F. B cells expressing IgM and IgD on their surface have undergone isotype switching.
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F. have not undergone
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The Fc receptors on macrophages and neutrophils recognize what?
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IgG
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The Fc portion of what binds to receptors on mast cells, basophils, and activated eosinophils?
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IgE
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Which Ig is secreted in mucous secretions, tears, and milk?
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IgA
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Which Ig is transferred into the fetal blood from the pregnant mother?
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igG
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Which Ig is found as a pentamer (or hexamer) in plasma?
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IgM
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Which Ig is found as a dimer?
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IgA
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T/F. IgM can be made after somatic hypermutation.
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F. made before
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What is the difference between allotype and idiotype?
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Allotype – alleic variant of C region; Idiotype – different V regions
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Peptides from the cytosol are bound to MHC class (I/II) and are recognized by CD (4/8) T cells. Peptides generated by intracellular vesicles are bound to MHC class (I/II) and are recognized by CD(4/8) T cells.
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Cytosol – MHC class I – CD8; vesicle – MHC class II – CD4
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What is the difference between what Th1 and Th2 cells do?
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Th1 – activate macrophages to kill intravesicular pathogens; Th2 – activate B cells to make antibody
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What protein transports peptides into the endoplasmic reticulum for MHC class I to present?
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TAP 1 & 2 (transporters associated with antigen processing)
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Peptides are generated in the (cytosol/ER) for MHC class I.
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cytosol
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Peptides are generated by what for presentation by MHC class I.
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proteasome
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The mycobacteria that cause leprosy and tuberculosis reside where? Their proteins are presented by MHC class (I/II).
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intracellular vesicles of macrophages; proteins presented by MHC class II
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Proteins that bind to surface immunoglobulins on B cells are presented by MHC class (I/II)
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II
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How are MHC class II moelcules prevented from binding peptides in the ER?
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invariant chain
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The MHC is located on which chromosome in humans?
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6
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What are MHC genes in humans called?
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Human Leukocyte Antigen (HLA)
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T/F. Cells express 1 MHC class 1 and 1 MHC class 2 proteins on their surfaces.
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F. 3 (or 6) different class I and 3-4 (6 or 8) different class II
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What are two methods that T cell receptors mediate transplant rejection?
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Peptide-dominant binding & MHC-dominant binding
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What are superantigens?
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proteins that are recognized by T cells without being processed into peptides
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Where do superantigens bind?
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outside surface of an MHC class II molecule that has already bound peptide
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Superantigens stimulate what?
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CD4 T cells; secrete tons of cytokines
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What is the first step in response to antigen
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receptor clustering
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What class of intracellular signal molecule does clustering of antigen receptors lead to?
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protein tyrosine kinases
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What are the three classes of amino acids that can be phosphorylated?
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tyrosine, serine/threonine, histidine
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How is signaling from the B-cell receptor complex transferred across the membrane?
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Ig-alpha & Ig-beta; ITAMs (immunoreceptor tyrosine-based activation motifs)
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The T cell (alpha/beta) chain is rearranged first.
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beta
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B lineage cells move toward the (central/peripheral) axis of the bone marrow cavity as they mature.
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move toward central
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What occurs during the pro-B cell stage?
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DJ in early pro-B cell stage; VDJ in the late pro-B cell stage
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What does the pre-B cell receptor consist of?
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m chain with surrogate light chain (intracellularly, mainly)
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Put in order: (immature/large pre/pro/small pre) B cells.
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pro; large pre; small pre; immature
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What occurs during the small pre-B cell stage?
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light chain rearrangement
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Immature thymocytes are found in the (cortex/medulla); mature thymocytes are found in the (cortex/medulla).
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Immature – cortex; mature – medulla
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What is the similarity between DiGeorge's syndrome and mice with the nude mutation?
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both lack thymus
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When is the rate of T cell production greatest?
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before puberty
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T/F. The production of new T cells stops at some point.
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F. continues throughout life, but slower
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T/F. T cell receptor genes are rearranged after they get to the thymus.
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T
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What does the pre-T cell receptor consist of?
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beta chains paired with a surrogate pre-T cell receptor alpha chain
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Does alpha chain rearrangement in T cells occur before or after double-positive thymocyte stage?
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after double-positive
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The (kappa/lambda) light chain is rearranged first.
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kappa
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T/F. Cells with only 1 antigen specificity are generated by one pre-B cell.
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F. many antigen specificities; large pre-B cells (with surrogate light chain) divides many times before light chain recombines
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What is the ratio of kappa to lambda light chains in humans/
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2:1; kappa rearranged first
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The (alpha/beta) chains of T cells rearranges first.
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beta (VDJ)
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T/F. A single alpha chain in a T cell can be paired with many different beta chains.
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F. other way around. Single beta chain can be paired with many different alpha chains (beta rearranges first)
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What occurs during the double negative phase of T cell rearrangemnet?
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DJ and VDJ of beta chain
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What occurs during the double positive phase of T cell rearrangement?
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VJ of alpha chain
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Alpha:beta and gamma:delta refer to what?
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T cell receptors
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Cells that fail to recognize the MHC molecules on the thymic epithelium never progress further than which stage?
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Double-positive stage
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Positive and negative selection refer to (B/T) cells.
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T cells in the thymus
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In the white pulp of the spleen (B/T) cells are clustered aroudn the central arteriole.
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T cells; B cell areas are located farther out
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Follicular dendritic cells (are/are not) leukocytes; (are/are not) phagocytic; (do/do not) express MHC class II proteins.
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not leukocytes; not phagocytic; do not express MHC class II
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How do follicular dendritic cells express antigen?
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capture in the form of immune complexes (complex of antigen, antibody, complement); remain on surface
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The Reed-Sternberg cell of Hodgkin's disease is a (B/T) cell.
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B cell
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What is a naïve T cell?
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mature recirculating T cells that have not yet encountered their specific antigens
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What are dendritic cells?
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Antigen-presenting cells that ingest and present antigen to T cells
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Macrophages display MHC class (I/II) molecules.
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II
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Cytotoxic T cells are MHC class (I/II).
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I
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Th1 and Th2 are CD (4/8) cells.
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CD4
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What is the difference between Th1 and Th2 cells?
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Th1 – pathogens inside macrophage & dendritic cell vesicles stimulate; Th2 – extracellular antigens stimulate
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Th(1/2) cells induce B cells to make IgG antibodies.
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Th1
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(CD8/Th1/Th2) activate the microbicidal properties of macrophages.
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Th1
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(CD8/Th1/Th2) activate B cells to produce IgM antibodies.
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both Th1 and Th2
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(CD8/Th1/Th2) cells stimulate production of different isotypes of Ig, including A & E.
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Th2
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What are the only cells that express both classes of MHC as well as the co-stimulatory cell-surface molecule?
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dendritic cells, macropahges, and B cells
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Where is antigen presented to naïve T cells?
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peripheral lymphoid tissues (dendritic cells travel)
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What are the most potent antigen-presenting cells for naïve T cells
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dendritic cells
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(L/P/E) selecin is expressed on leukocytes. (L/P/E) selectin is expressed on vascular endothelium.
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L – leukocytes; P, E on vascular endothelium
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In addition to antigen-specific receptor and CD4 or 8 co-receptor binding, what else is necessary to trigger T cells into action/
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Co-stimulatory signal
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How is a state of anergy for T cells created?
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antigen binding to the T cell receptor in the absence of co-stimulation; (anergy – T cell becomes refractory to activation by specific antigen even presented by APC)
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What is a B7 molecule?
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Co-stimulatory molecule necessary for T cell activation
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What are Langerhans' cells of the skin?
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immature dendritic cells
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After a macrophage ingests an organism, it presents its peptides on MHC class (I/II) molecules.
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class II
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The proliferation and differentiation of T cells is driven by which IL?
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IL2 (Hot T-Bone stEAk)
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How do cyclosporin A and FK506 (tacrlimus) suppress adaptive immune responses?
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inhibit IL2 production
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How does rapamycin (sirolimus) work?
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inhibit signaling through the IL2 receptor
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What is the difference between a naïve T cell and an armed effector T cell in the context of encountering its specific antigen?
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no need for co-stimulation for armed effector T cell
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When does a CD4 T cell decide whether to be a Th1 or Th2 cell?
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after encounter with antigen
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Th(1/2) leads to cell-mediated immunity and production of opsonizing antibodies (IgG); Th(1/2) leads to humoral immunity, especially IgM, IgA, and IgE.
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Th1 – cell-mediated immunity; Th2 – humoral immunity
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A Th(1/2) mediated immunity in the context of leprosy is a disaster.
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Th2 – disaster b/c antibodies produced cannot reach intracellular bacteria
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The main cytokine released by CD8 effector T cells is what? What can it do?
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IFN-gamma; block viral replication or lead to the elimination of virus from infected cells without killing them
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What happens to the DNA of cells undergoing apoptosis?
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fragmentation of nuclear DNA into 200-BP pieces by nucleases that cleave between nucleosomes
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What cytotoxic proteins are in the lytic granules of CD8 (cytotoxic) T cells?
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perforin, granzymes, & granulysin
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Mycobacteria can be eliminated when the macrophage is activated by a (CD8/Th1/Th2) T cell.
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Th1
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Macrophage activation is the principal effector action of (CD8/Th1/Th2) cells.
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Th1
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How is PCP pneumonia addressed by T cells?
|
activation of macrophages by Th1 cells; cause of death in AIDS b/c deficiency of CD4 T cells
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What is the most characteristic cytokine produced by armed Th1 cells on interacting with their specific target cells?
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IFN-gamma
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Why are Th2 cells inefficient macrophage activators?
|
produce IL-10 (deactivate macrophages); do not produce IFN-gamma
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Helper T cells that triger B cell activation into plasma cells are what?
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Th2 class of CD4 cells (also Th1 T cells, but a lesser extent)
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How can antibodies lead to the phagocytosis of pathogens?
|
recognized by Fc receptors on phagocytic cells; complemenet system
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What leads to somatic hypermutation and isotype switching?
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interaction of B cells with helper T cells
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B cells present antigen in MHC class (I/II)-bound molecules.
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II
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T/F. All B-cell responses require armed peptide-specific helper T cells.
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F. many microbial constituents, such as bacterial polysaccharides, can induce antibody production in the absence of helper T cells
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What happens to the CD4 T cell before it activates the B cell.
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interact with antigen-presenting dendritic cell or macrophage to becomes armed helper T cell
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T/F. The B cell that a T helper cell activates produces antibodies to the same protein that the T cell recognizes a part of.
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F. can be different
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What are haptens?
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small chemical groups that cannot elicit antibody responses on their own ; when coupled to a carrier protein, they become immunogenic
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Which cytokines made by armed effector T cells are responsible for activating B cells?
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CD40 ligand & IL4
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What is the most abundant Ig in plasma?
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IgG
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Where do proliferating B cells go?
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germinal center
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Where does somatic hypermutation and isotype switching occur?
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germinal center
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What types of DNA changes does somatic hypermutation involve?
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single bp changes (1/1000 per cell division)
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Where do plasma cells produce antibody?
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after becoming plasma cell, it moves to the bone marrow
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T/F. Antibodies cannot be produced without isotype switching.
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F. IgM antibodies produced before isotype switching
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Which class of Ig is bound avidly by receptors on mast cells?
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IgE
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Where are the principal sites of IgA synthesis and secretion?
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gut, respiratory epithelium, lactating breast, salivary & tear blands
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Which Ig are transferred from mother to baby?
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IgA in breast milk; IgG across plaenta
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What is passive immunization?
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transfer of antibodies directly to protect against a toxin
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Antibodies initiate complement activation by which pathway?
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classical pathway
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Which Ig can initiate the classical complement activation pathway?
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IgM & IgG
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Which component of the complement cascade binds to the Fc region of IgM or IgG bound to a pathogen?
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C1q
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Cells with viral proteins on their surface bound by antibodies are destroyed by what?
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NK cells
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What causes inflammation?
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activation of resident macrophages; secretion of cytokines and chemokines (esp. TNF-alpha); activation of complement
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CD4 T cells stimulated in the presence of IL-12 and IFN-gamma tend to develop into Th(1/2) cells. Why
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Th1; IFN-gamma inhibits the proliferation fo Th2 cells
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CD4 T cells activated in the presence of IL-4 and IL-6 tend to differentiate into Th(1/2) cells.
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Th2; IL-4 inhibit the generation of Th1 cells
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What is the difference between Th1 and Th2 T cells?
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Th1 – activate macrophages; Th2 – activate B cells
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IL-10, a product of Th(1/2) cells, can inhibit development of Th(1/2) cells.
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product of Th2; inhibit development of Th1
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IFN-gamma, a product of Th(1/2), can inhibit development of Th(1/2) cells.
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product of Th1; prevent activation of Th2
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Large amounts of peptide that achieve a high density on the surface of antigen-presenting cells tend to stimulate a Th(1/2) response; low density elicits a Th(1/2) response.
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High – Th1; Low – Th2
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What are examples of pathogens that evade complete clearance and persist for the life of the host?
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Leishmania, Toxoplasma, and herpes viruses
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The dominant antibody isotype of the mucosal immune system is Ig what?
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IgA
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T/F. In blood, IgA is found as a dimer.
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monomer in blood. Dimer in mucosal secretions.
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What are M cells?
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specialized epithelial cells in Peyer's patches (small intestine) with microfolds on their lumenal surface
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What are Th3 T cells? What do they do? What do they secrete?
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regulatory T cells; actively suppress antigen-specific responses; produce IL-4, IL-10, TGF-beta
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Which IL's maintain memory T cells?
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IL7 (in general); IL15 for CD8 T cells
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Maximal levels of memory T cells occur how long after an infection? Memory B cells?
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T – 5 days; B – 1 month
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T/F. T cell receptors undergo somatic hypermutation.
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F. do not
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How can the response of an Rh- mother be prevented when she has an Rh+ child? Will it work when she has memory B cells to the Rh antigen?
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Anti-Rh antibody given to the mother before her reaction; not work if already has memory B cells b/c more sensitive and higher affinity
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What is the difference between antigenic drift and antigenic shift in the context of influenza?
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Drift – point mutations in genes encoding hemagglutinin & neuraminidase; shift – reassortment of segmented RNA genome & related animal influenza viruses
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How does trypanosomes escape the immune system and cause sleeping sickness?
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changes in major surface anitgen occurs repeatedly within a single infected host
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Why is it difficult for CD8 T cells to respond to viral infections in neurons?
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neurons carry very low levels of MHC class I molecules (helps b/c neurons do not regenerate or regenerate slowly)
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How does toxoplasma make itself invisible to the immune system?
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generate its own vesicle
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Which is worse: tuberculoid or lepromatous leprosy?
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lepromatous worse: cell-mediated immunity profoundly depressed
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Increased risk of infection by pyogenic bacteria can be caused by what?
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deficiency of antibody, complement, or phagocytic function
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What is special about pyogenic bacteria that allows their escape from macrophage sand neutrophils?
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have polysaccharide capsules
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What gene is defective in Bruton's X-linked agammaglobulinemia and how is disease caused?
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Bruton's tyrosine kinase; lead to arrest at the pre-B-cell stage
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When do infants start to produce IgG?
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6-12 months of age
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Defects in the membrane-attack components results exclusively in suscewptibility to what?
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Neisseria species
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What's wrong in chronic granulomatous disease?
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phagocytes cannot produce superoxide radical (NADPH oxidase system)
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What's wrong in Chediak-Higashi syndromein the context of immunodefiiency? What is the clinical presentation of this disease?
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problem with vesicle formation; cannot fuse lysosomes with phagosomes; partial albinism, abnormal platelet function
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Severe combined immunodeficiency is associated with what defect?
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T cell defects
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What's wrong in DiGeorge's syndrome?
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thymic epithelium fails to develop normally
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Epstein Barr virus infects what cells?
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B cells
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Why do people with epstein-barr virus infections not develop cancer usually?
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actively controlled by cytotoxic T cells
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Surgical removal of the spleen is associated with a lifelong predisposition to overwhelming infection by what?
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Strep. Pneumoniae
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What cells do HIV infect?
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CD4 T cells, dendritic cells, and macrophages
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What component of the HIV virus binds to CD4?
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gp120
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What are the two major co-receptors for the HIV virus?
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CCR5 and CXCR4 (on activated T cells)
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What component of the HIV virus causes fusion of the viral envelope to the plasma membrane?
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gp41
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Infection of CD4 T cells via _____ occurs early in the course of infection; late in infection, infection occurs via _____ .
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Early – CCR5; Late – CXCR4
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What characterizes a lentivirus?
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Lenti – slow; slow replication
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What is the half-life of the HIV virus in productively infected cells?
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2 days
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What are early infections when the CD4 T cell count is low in AIDS?
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Candida & Tuberculosis
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What are late infections when the CD4 T cell count is low in AIDS?
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varicella zoster, B-cell lymphomas; Kaposi's sarcoma
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What are the infections in the final stages of AIDS infection?
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Cytomegalovirus & M. avium complex
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Allergy is caused by which Ig?
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IgE
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IgE is involved in protection against what?
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parasitic worms
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Which type of hypersensitivity is allergy?
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Type I hypersensitivity
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IgE binds to the surfaces of what cells?
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mast cells
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IgE antibody production requires Th(1/2) cells that produce which IL's?
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Th2 cells; IL4 & 13
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IgE antibody production can be inhibited by Th(1/2) cells that produce ___ .
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Th1 cells; IGN-gamma
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Which IL's favor development of a Th2 response?
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4, 5, 9, 10, 13
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Which factors favor a Th1 response?
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IL-12, Th1
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What is atopy?
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exaggerated tendency to mount IgE responses to a wide variety of environmental allergens
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IgE is fixed on the surfaces of what cells?
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mast cells, basophils, eosinophils
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Which IL causes increased production of eosinophils?
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IL-5
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Systemic anaphylaxis due to penicillin is due to which Ig?
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IgE
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In desensitization to allergy, what is the mechanism behind treatment?
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shift antibody response away from one dominated by IgE toward one dominated by IgG
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What are type II hypersensitivity reactions?
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drug binds to cell surface and serves as a target for anti-drug IgG antibodies
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What are type III hypersensitivity reactions?
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deposition of antigen:antibody aggregates or immune complexes in particular tissues and sites
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What is an Arthus reaction?
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immune complex binds to leukocytes; local inflammatory response with increased vascular permeability; polymorphonuclear leukocytes to enter the site from local vessels
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Serum sickness is an example of a type what hypersensitivity reaction? What is serum sickness? What is its timeframe?
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III (3); injection of large quantities of a poorly catabolized foreign antigen; 7-10 days after injection b/c switch from IgM to IgG
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What occurs in type 4 hypersensitivity reactions?
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Delayed-type hypersensitivity; antigen-specific effector T cells (CD4 Th1 and CD8)
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The tuberculin test is an example of which type of hypersensitivity?
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4; delayed-type hypersensitivity
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How does the immune system distinguish self ligands from nonself ligands?
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encounter when lymphocyte is immature; high and constant concentration of ligand, binding in the absence of co-stimulatory signals
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Antibodies against what are present in Graves' disease?
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Thyroid-stimulating hormone
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Antibodies against what are present in Hashimoto's thyroiditis?
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thyroid peroxidase
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What is epitope spreading?
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antoimmunity to a single epitope can lead to more widespread autoimmunity
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What are the immunologically privileged sites in the human?
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brain, eye, testis, uterus
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Which cytokines do Th1 cells secrete?
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IGN-gamma and TNF-alpha
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What are CD4 CD25 T cells?
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regulatory T cell; suppresses immune response
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Hashimoto's thyroiditis is a result to autoantibodies against what?
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thyroid peroxidase and thyroglobulin
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Graves' disease is an example of which type of hypersensitivity? What's the problem in this disease?
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Type 2; antibody binding to thyroid stimulating hormone receptor; excessive production of thyroid hormone
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Goodpasture's syndrome is an example of a type what hypersensitivity reaction? What's the problem?
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Type 2; antibody against basement membrane collagen
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In autoimmune diabetes mellitus, what causes damage to the insulin-secreting beta cells?
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CD8 T cells
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How long does it take for an allograft to be rejected? What about a second graft?
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10-13 days; 6-8 days
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One sibling in how many should be HLA-identical?
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1 in 4
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What are minor histocompatibility antigens?
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polymorphisms in proteins inside the cells of different members of a species
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What causes direct allorecognition in the context of tissue transplant?
|
donor antigen-presenting cells leaving the grafting and migrating to regional lymph nodes; activate host T cells
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What causes indirect allorecognition in the context of tissue transplant?
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uptake of allogeneic proteins by the recipient's own antigen-presenting cells and presentation to T cells
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What causes hyperacute graft rejection?
|
preexisting alloantibodies
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What is the half0life for functional survival of renal allografts?
|
8 years
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How does the mixed lymphocyte reaction work?
|
lymphocytes from a potential donor are mixed with irradiated lymphocytes from the potential recipient; look for T cell division
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In general, how to steroids work?
|
bind intracellular receptors that regulate transcription of specific genes
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What are side effects of corticosteroids?
|
fluid retention, weight gain, diabetes, bone mineral loss, thinning of skin
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What are the three cytotoxic drugs most commonly used as immunosuppresants/
|
azathioprine, cyclophosphamide, mycophenolate
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How does azathioprine work?
|
block de novo synthesis of adenosine & guanosine monophosphate; inhibit DNA synthesis
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How does cyclophosphamide work?
|
alkylates DNA (nitrogen mustard)
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What are side effects of cyclophosphamide?
|
bladder: hemmorhage & neoplasia
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How do cyclosporin and tacrolimus work?
|
inhibit calcineurin (phosphatase); reduce expression of IL-2
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How does rapamycin work?
|
block signal transduction triggered by ligation of growth factor receptors; blocks proliferation of T cells
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Regulatory T cells secrete what to downregulate the immune response?
|
IL-10 and TGF-beta
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What is herceptin (trastuzumab)?
|
huanized monoclonal antibody that targets growth factor receptor; used in breast cancer
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T/F. CD8 T cells are generated by inactivated viruses. Why/how?
|
F. not generated; inactivated viruses do not produce proteins in the cytosol, so cannot be presented by MHC class I molecules
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IL-12 encourages a Th1(1/2) response.
|
Th1
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What are Toll-like receptors important for?
|
Dorso-ventral patterning & host defense
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What is the difference between jawed fish and jawless vertebrate fish in terms of immune system?
|
jawed fish can mount adaptive immune response; jawless cannot
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