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50 Cards in this Set
- Front
- Back
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what is immunology?
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the science of self-nonself discrimination
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functions of immunology
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1. recognition mediated by MHC
2.effector (t-cells and b-cells) 3.regulation 4.memory |
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what is 'self'
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dictionary - material that is part of an individual organism
the body does not normally mount immune responses against its self antigens, at least not in quantities sufficient to harm the body |
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what is 'nonself'
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dictionary - material that is foreign to the body of an organism
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what are the 4 threatening situations that individuality is jeopardized?
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1. parasitism, which is a threat to the individual's survival
2.organ and tissue damage, which is a threat to the organism's integrity and individuality 3.neoplasia, which is a threat to both uniqueness and survival 4. fusion of genetically disparate individuals in colonial animals |
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Neoplasia
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an abnormal, incompetent growth in a tissue or organ, typically forming a separate mass. Such a growth is called a neoplasm, also known as a tumour.
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Elie Metchnikoff
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russian embryologist, first presented his phagocytosis theory of host defensed
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lymphocytes
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providing the cellular basis for immunological specificity
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cytokines
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shown to orchestrate cellular communication, to promote and/or regulate most immunological reactions, and to play key roles in promoting host defense and immunopathology
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what is the single progenitor that leads to all effector cells?
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pluripotent hematopoietic stem cell in the bone marrow
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bone marrow progenitor stem cell leads to....
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3 lineages
1. lymphatic 2. myeloid/macrophage 3.erythrocyte need all lineages to reach professional APCs |
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what is MSG?
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macrophage specific gene
needed to produce macrophages |
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what are the steps of clonal selection?
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-each lymphocyte bears a single type of receptor with a unique specificity
-interaction btw a foreign molecule and a lymphocute receptor capable of binding that molecule with high affinity leads to lymphocyte activation -the differentiated effector cells derived from an activated lymphocyte will bear receptors of identical specificity to those of the parental cell from which that lymphocyte was derived -lymphocytes bearing receptors specific for ubiquitous self molecules are deleted at an early stage in lymphoid cell development and are therefore absent from the repertoire of mature lymphocytes |
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Nature of the antigen is the major variable...
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charlie janeway
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broad categories of disease-causing microbes (pathogens)
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1. viruses
2. bacteria 3. fungi - eukaryotes 4. parasites - unicellular and multicellular eukaryotes |
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key difference btw antibodies and t-cell receptors (TCRs)
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TCRs are bound to the cell membrane
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what are the professional APCs?
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Dendritic (myeloid)
Macrophage (myeloid) B lymphocyte (lymphoid) |
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activated function of dendritic cell
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antigen uptake in peripheral sites
antigen presenting phagocytosis and initiation of immune response |
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what kills the infected cells?
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CTLs - cytotoxic t lymphocytes
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what does a viral cell target in the host?
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ribosomes, to create more viruses
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What kind of antigens are presented by MHC I
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intracellular
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what kind of antigens are presented by MHC II
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extracellular
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activated function of macrophage
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phagocytosis and activation of bactericidal mechanisms
able to process antigens and produce peptide antigens antigen presentation |
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what is the precursor for macrophages?
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monocyte
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the antigen receptors found on the macrophage are apart of which immune system?
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innate
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what are receptors found on the macrophage?
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mannose
LPS (CD14) TLR-2 TLR-4 Glucan scavenger |
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where are lymphocytes activated?
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int he lymph node, then head back to site of infection
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how are t lymphocytes activated?
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immature dendritic cells reside in peripheral tissues
then migrate via lyphatic vessels to regional lyphm nodes then mature dendritic cells activate naive t cells in the lymphoid organs (lymph node) |
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how do lymphocytes and lymph return to the blood
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via the thoracic duct
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antigen binding region of MHC I
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only alpha chain used, still has beta chain
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antigen binding region of MHC II
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made up of both alpha and beta chain
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pathway for cytosolic pathogens
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degraded in the cytosol
bound by MHC I found on any cell then presented to EFFECTOR CD8 T cells leading to the death of the infected cell |
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pathway for cross-presentation of exogenous antigens
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broken down in the cytosol by retrotranslocation
bound by MHC I and presented to naive CD8 t cells the presenting cell, usually dendritic, activates the CD8 cell |
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pathway for intravesicular pathogen
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degraded in the endocytic vesicles with a acidic pH
bound by MHC II found on macrophage then presented to CD4 T cells leads to activation to kill intravesicular bacteria and parasites |
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pathway for extracellular pathogens and toxins
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degraded in the endocytic vesicles by acidic pH
bound by MHC II and presented to effector CD4 t cells activation of b cells then occurs to secret immunoglobins to eliminate extracellular bacteria/toxins |
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what happens after a virus infects the cell?
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viral proteins are synthesized in the cytosol
peptide fragments of the viral proteins are bound by MHC I in the ER bound peptides are transported by MHC I to the cell surface |
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how do you get the peptide into the ER
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must produce peptides that degrade the virus so they can be transported into the ER
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adaptations of viruses that block the immune response
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blocking the peptide from entering the ER (block/inhibit TAP from binding the peptide)
retention of MHC I in the ER (in hibitor of tapasin, block tapasin) degradation of MHC I binds MHC I at cell surface which interferes with recognition by APCs |
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TAP
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peptide transporter that allows antigen peptides to enter the lumen
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what is different about the immunal proteosome vs the constitutive?
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has 2 p28 caps on the end
3 substituted beta subunits: lmp-1, lmp-2, mecl-i |
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2 ways antigens enter cell for binding with MHC class II
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bacterium infects macrophage and enters into a vesicle, producing peptide fragments that become bound by MHC II, and are then transported to the surface
antigen bound by b-cell surface receptor becomes internalized and degraded to peptide fragments. The fragments bind to MHC II and are transported to the cell surface. |
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vesicular pathway for pathogens
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antigen is taken up front he extracellular space into the intracellular space encasing it in a vesicle.
in the stages the vesicle is of neutral pH, which keeps the endosomal proteases inactive acidification of vesicles activates proteases to degrade antigen into peptide fragments the vesicle containing the peptides fuses with vesicles containing MHC II |
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what is the invariant chain?>
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binds in the groove of MHC II while in the ER.
the chain is then cleaved twice leaving a small fragment (CLIP) bound to the MHC it blocks the binding of peptides and misfolded proteins |
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How is the invariant chain cleaved to leave CLIP behind?
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through acidic situations in an endosome
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what is the purpose of the CLIP peptide?
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there are endocytosed antigens that are degraded to peptides in the endosomes and CLIP blocks the binding of these peptides to the MHC II molecule
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how is the CLIP peptide removed from MHC II?
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HLA-DM binds to the MHC II molecule, releasing the CLIP allowing other peptides to come in and bind with MHC, after which the MHC complex moves to the cell surface.
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where do the stages of the invariant chain take place?
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it first binds the MHC II in the ER
it is cleaved forming CLIP in the endosome CLIP is removed in the endosome |
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CD8 T Cells
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cytotoxic (killer) t cells or CTLs
endogenous pathogens binds to MHC I + antigen |
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CD4 T Cells
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TH1 and TH2 cells (helper)
interacts with infected macrophages and B-cells exogenous pathogens |
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difference btw TH1 and TH2
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TH1 - proinflammatory and activates macrophages
TH2 - b-cell helpers |
