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81 Cards in this Set
- Front
- Back
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Define determinant or epitope
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the smallest identifable part of an antigenic molecule that can be recognized by a given T or B cell receptor
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antigen
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An antigen is a molecule that reacts with a specific component of adaptive immunity. These components are either antibody molecules or antigen-binding receptors on B or T lymphocytes
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immunogen
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Immunogens are antigens that can induce an immune response
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hapten
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Haptens are small molecules that are not naturally immunogenic; the best examples are small drugs
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tolerogen
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are molecules that can stimulate immune responses and serve as targets of those responses , but on re-exposure reduced responsiveness
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Pattern-recognition receptors
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Used by the innate system that are genetically encoded and expressed by a variety of leukocytes
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Antigens may be
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proteins, carbohydrates, lipids,or combinations such as glycoproteins and glycolipids
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epitope or determinant
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the smallest identifiable part of an antigenic molecule that can be recognized by a T or B cell receptor
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immunogens
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antigenic molecules that can both stimulate an immune response and be a target of an immune response
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haptens
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small molecules that by themselves cannot stimulate immune responses but can be recognized by the immune system if bound to an immunogenic molecule
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what cell surface molecules are useful in distnguishing leukocytes?
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Immunoglobins, CD cluster of differentiation receptors, major histocompatibility MHC molecules
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superantigen
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molecule that stimulates T cell subsets by binding to parts of the T cell receptor other than the antigen binding groove
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In adaptive immunity antigenic determinants are recognized by....
Innate immunity receptors |
A. B cell receptor and T cell receptors ,
B. Toll receptors and Broad Molecular Patterns |
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If a person has blood type AB, what antibodies do they produce
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neither anti-A or anti-B
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what are some of the effector functions of immunoglobins?
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-opsonization by binding to FcR to aid in killing bacteria
- complement fixation -passage through placenta |
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what are the five classes of Immunoglobins?
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IgG, IgM, IgD, IgA, IgE
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For the structure of each Ig molecule how many domains are present?
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Two on the light chain: VL & CL
Four on the Heavy chain: Vh & CH1, CH2, CH3, and maybe CH4 |
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How does papain digest Ig?
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Papian cleaves Ig in the hinge region of the molecule.
Valence=1 because the is only one antigen binding site and specifity is detemined by Vh &VL also the Fc region is still in tack |
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Pepsin digestion of Ig?
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F(ab')2, valence=2
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what region of Ig mediate effector function?
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Constant regions
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what are the two types of light chains?
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Kapppa or lambda
60:40 ratio except in malignacny like multiple myeloma or B cell leukemia |
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what are some characteristics of IgG?
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-It has only one unit
-Four subclasses -major serum Ig -Can cross the placenta and does not requires Ag binding -Fixes complement(IgG4) _Binds to Fc receptors(IgG2,IgG4) -Longest half-life |
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what are the characteristics of IgA?
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-in serum it is a monomer
-in secretions(slgA) it is larger- second highest in serum, - dimer with or without J chain -with secretory componect |
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slgA found in.....
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tears, saliva, gastric and pulmonary secretions
-does not fix complement -binds to Fc receptors on some cells |
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Where are IgD found?
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B cell surface Ig (usually with IgM monomer)
-does not bind complement |
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IgE antibody has what extra?
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- exta domain
-least common serum Ig - Allergic rxns -In parasitic infections they bind to Fc receptors of eosinophils - does not fix complement |
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isotypic
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the class or subclass of an Ig
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allotype
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a structural site on the heavy chain of a particular Ig class or onthe light chain that differs among indiv or inbred lines of the same species Used as markers
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idiotype
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an antigenic determinant on a specific antibody, characteristic of that antibodyans different from others even of the same isotype and allotype, idiotype are usually located in or near the antigen binding site
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allellic exclusion
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The inactivation of one set of the chromosomes in B cell, because only one kind of light chain and one kind of heavy chain can be expressed
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what is the normal response to an immunogen?
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Polyclonal response-many clones of B cells making different antibodies
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where are monoclonal antibodies produced ?
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Monoclonal antibodies are produced in the lab by making mouse hybridomas- product of one B cell all molecules identical
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How to generate a polyclonal immune response?
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-Immunize an animal or a human with an immunogen
-Collect serum (separated from clotted blood) at a time when antibodies are expected -Check serum for antibodies by serological tests -If antibodies are found=antiserum -If antibodies not found: Boost a second time Use an adjuvant |
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Heterogeneous Ig
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Ig antibodies are normally heterogeneous, but there are five classes and subclasses
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Homogeneous Ig
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Results from Myeloma
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multiple myeloma
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-Malignancy of a B cell
-Patient produces extremely high levels of IgM (Waldenstrom’s macroglobulinemia), IgG, or IgA (occasionally IgD or IgE) -High serum levels due to large number of monoclonal population B cells Results in immunodeficiency and other symptoms |
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Nature of Ag/Ab Reactions due to epitope-paratope interactions
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Non-covalent interactions-
Hydrogen bonds Electrostatic bonds Van der Waal forces Hydrophobic bonds |
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what are the four types of hypersentivity reaction?
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Type I mediated by IgE
Type II mediated by antibodies Type III medatied by immune complexes TypeIV mediated by cells |
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Hypersentivity occurs as a result of...
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secondary response
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Homocytotropic
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IgE binds to Fc receptors FcRe on cells in the absence of antigen
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What happens when IgE antibodies on the surface of mast cells,basophils are cross linked by allergen?
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1. the preformed mediator histamine is rapidly released
2. synthesis of other non-preformed mediators is initiated |
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what is atopy?
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genetic tendency to make IgE in response to allergens
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What is the normal concentration of IgE in the blood?
half-life in circulation? half-life bound to cells? |
- <1ug/ml in the blood
- 2 to 3 days in circulation - 3 to 4 wks bound to cells |
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IgE can be measured by?
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RIST-total circulating IgE
RAST-specific circulating IgE |
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Name the late phase derived mediators od hypersensitivity reaction?
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Leukotrienes- C4,D4,and E4 generated by the metabolism of arachidonic acid,
Prostaglandin D2 Platelet activating factor |
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True or False. Endothelial cells are important components of the innate immunity be/c they release proteins and peptides known as cytokines and chemokines
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True
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These are lymphocytes that have the own receptors KIR and KAR that recognize virally infected cells and tumor cells
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NK lymphocytes part of the adaptive immune response can directly kill infected cells without phagocytosis
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Toll receptors
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These are receptors that recognize PAMP which include LPS,lipopeptide,peptidoglycan which are unique to bacteria and unmethylated DNA and dsRNA which are unique to viruses
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True or False. Epithelial and endothelial cells secrete antibacterial peptides such as defensins and intergrins
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True
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what are the 3 primary effector cells in the innate immune system?
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Macrophages(monocytes), neutrophils, and NK cells
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which cytokines are secreted by macrophages ?
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TNF alpha and IL-1 which regulate fever and effect the hypothalamus.
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how many days does the neutrophil live?
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1 to 3 days - they are the key mediators of acute inflammation
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interferon
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A class of small protein and glycoprotein cytokines (15–28 kD) produced by T cells, fibroblasts, and other cells in response to viral infection and other biological and synthetic stimuli. Interferons bind to specific receptors on cell membranes; their effects include inducing enzymes, suppressing cell proliferation, inhibiting viral proliferation, enhancing the phagocytic activity of macrophages, and augmenting the cytotoxic activity of T lymphocytes.
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what are the three main functions of acute inflammatory response?
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-Acute inflammatorey exudate which carries proteins, fluid, and cells from local blood vessels into damaged area to mediate local defenses
- destruction of the infective agent -damaged tissue can be broken down and removed |
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what are some physical changes that will happen in inflammatory response?
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-changes in blood flow
- increased permeability of blood vessels - escape of cells from the blood into the tissues |
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define hypersensitivity?
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-it occurs when an altered state of immunoliogical responsiveness causes an inappropriate or excessive immune rx which damages the tissues
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Stages of B cell development: combination of gene segments encoding heavy chain u had begun , but heavy chain not yet produced
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Pro B cell
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This stage of B cell development: heavy chain u is completely rearranged; heavy chains are in the cytoplasm ; surrogate light chain
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Pre B cell
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Stage of B cell: expression of monomeric IgM and serves asn the antigen receptos for the cell
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Immature B cell
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These immature B cell mature in the spleen and express both IgM and IgD- they form the BCR complex
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Mature B cell
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Mature B cells are positive for
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CD19 and CD20
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When antigen binds to the BCR on mature B cell....
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B cell divide and differentiate
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After antigen Binds to Bcell
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- B lymphoblast is formed, more ribosomes to make Ig:n clonal expansion
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What happens after 4-5 days to the B lymphoblast
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it becomes a plasma cell for 2-3 days then die
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memory cells
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the portion of lymphoblast that do not become plasma cells; they have IgG, IgA and IgE on their surface
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CD 10
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on pre B cells
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CD 34
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-on Stem cells
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Bcell receptors
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- Fc Receptor
- Complement receptor - MHC molecules |
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How can a T cell recognize an antigen?
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The antigen must be present on a cell membrane, in the binding groove of either class I or class II MHC
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what are the two types of antigen receptors?
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-alpha beta ( mostly)
-gamma delta |
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The Tcell receptors are also associated with what that is involved in signal transduction?
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The CD3
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Early cell differentiation marker for both B and T cell
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-CD1
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Found on all human T cells regardless of stage of diffferentiation
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- CD2
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Is an enzyme that is present only in cortical thymocytes and early progenitors of B cells. Plays a role in generating diversity of V sequences in the BCR and TCR
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TdT
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Binds to class II MHC molecules
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CD4 ( helper or DTH)
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Binds to class I MHC molecules
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CD8
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Class I are found where
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-on all cells exceptn neurons and striated muscles
-unique alpha chain, unique to self w/ constant beta2 microglobin |
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Class II are found
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- B cells , macrophages, dendritic cells, activated Tcells
- have a alpha and beta chain |
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The process by which cells with receptors that do no recognize self or bind too strongly to self MHC are eliminated
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Positive selection
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what is another name for MHC?
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HLA human leukocyte antigen
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true or false. gene rearrangement occurs prior to antigen exposure
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true
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