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44 Cards in this Set
- Front
- Back
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Are all antibodies immunoglobulins? Are all immunoglobulins antibodies?
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All antibodies are immunoglobulins, but there are other types of immunoglobulins
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What are the two major functions of antibodies?
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1. Specific binding to antigen
2. Participation in effector reactions, like allergic reactions, cell activation, complement fixation |
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What are the major classes of human immunoglobulins? Provide subclasses where relevant
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GAMED:
IgG --> 1, 2, 3, 4 IgA --> 1, 2, slgA IgM --> None described IgE --> None described IgD --> None described |
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What are isotypes?
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Differences in the main immunoglobulin classes; these are the same in all individuals of the same species
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What are allotypes?
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Small differences between individuals of the same species in AA sequence of similar immunoglobulins; reflect differences in allelic genes
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What are idiotypes?
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Unique to an immunoglobulin molecule produced by a particular clone of an immunoglobulin producing cell; generally associated with the antibody combining site
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What are the two main types of light chain?
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Kappa and lambda
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What is the major immunoglobulin in the bloodstream?
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IgG
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What are the 4 functions of IgG?
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1. Toxic neutralization
2. Agglutination 3. Bacteriolysis 4. Opsonization |
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Which immunoglobulins are capable of activating complement?
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IgG (need at least two), IgM
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What two enzymes were used in the cleavage of IgG?
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1. Pepsin
2. Papain |
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What does Fab stand for? Fc?
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Fab --> Fragment antigen binding; the fragments of cleaved IgG capable of binding antigen
Fc --> Fragment crystallizable; the fragment of cleaved IgG that could be crystallized |
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In terms of light and heavy chains, what is Fab composed of? Fc?
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Fab --> Light and heavy chains
Fc --> Just heavy chains |
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In IgG, what are the domains of the heavy chain? The light chain?
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Heavy chain: one cariable (VH) and three constant (CH1, CH2, CH3)
Light chain: One variable (VL) and one constant (CL) |
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What allows the two Fab regions of IgG to operate independently?
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The hinge region
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What Ig is the most conserved in evolution?
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IgM
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IMPORTANT: What is the J chain? What process requires it? What cells synthesize it?
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The J chain is a protein segment seen in IgM and IgA. It it necessary for initiating and maintaining the polymerization of IgM/IgA. It is synthesized by plasma cells producing IgM and IgA.
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What is the first Ig to appear in the immune response?
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IgM
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What is the first Ig to appear be produced by the neonate?
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IgM
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What is the major Ig receptor on teh B cell?
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IgM
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What are the various forms IgA can exist in?
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1. Monomer
2. Dimer 3. Trimer 4. Secretory IgA (sIgA) |
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What is the structure of sIgA?
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Double Y shaped structure consisting of:
Two monomers linked through the C terminal end, a J chain, and a secretory component Both ends of Y a bit like IgG |
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What synthesizes the secretory component (SC) of IgA?
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Epithelial cells, *NOT* plasma cells
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What is the biological activity of IgA?
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1. Antibody activity in extravascular secretions
2. Transfers maternal immunity tothe neonate post-partum in colostrum 3. Standard (toxic neutralization, opsonization (?), agglutination, but NOT bacteriolysis) |
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What is the major function of IgE?
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To arm mast cells and basophils for their role in allergic reactions
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What immunoglobulin is associated with allergy?
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IgE
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What is the function of IgD?
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Acts as antigen receptor on B cells
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What immunoglobulin is really difficult to study? Why?
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IgD; very low concentration in serum
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What is an immunogen? What is an antigen?
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Immunogen: A compound capable of inducing an immune response
Antigen: A compound able to combine with elements of acquired immunity |
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Are all antigens immunogens? Are all immunogens antigens?
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All immunogens are antigens, but not all antigens are immunogens.
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What is an example of an antigen that is not an immunogen?
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Haptens
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IMPORTANT: What is another term for epitope?
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Antigenic determinant
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IMPORTANT: What is an antigenic determinant?
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Region of molecule that is involved in binding with the combining site of an immunoglobulin
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IMPORTANT: What dictates the number of epitopes seen on a molecule?
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Size and chemical complexity of the molecule
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What dicatates the foreigness of a particular antigen? What is a qualification here?
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The amount of phylogenetic difference between the host and the antigen. An important qualification is that the host can have an immunological response to something from the same species.
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What is the general relationship between the size of the Ag and the strength of the immunogen?
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No good relationship
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The larger the size of the immunogen, the _____ (blank) the immunogen. Possible reasons?
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The larger the size, the better the immunogen.
Possible reasons: Larger size = increased chemical complexity, more antigenic determinants, better uptake by macrophages |
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What are some reasons for the connection between chemical complexity of Ag and strength of immune response?
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1. Cooperation of epitopes recognized by T cells and those recognized by B cells
2. Better chance of having epitopes recognized by helper T cells 3. Better uptake by macrophages |
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What is an adjuvant? Can they make a non-immunogenic compound immunogenic? Can they act as immunoigenic carriers?
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A substance that, when mixed with an immunogen, enhances the immune response to that immunogen.
No and no. |
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What is the difference between a T cell dependent antigen and a T cell independent antigen?
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Dependent --> Interact with T cells and stimulate their functional response; interaction of B cells with antigen requires the presence of specific helpter T cells
Independent --> Interact poorly with T cells; stimulate B cells with limited T cell participation |
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True or false: most proteins are thymic-indepdendent antigens
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False; most are thymic-dependent
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What is a general principle of the chemistry of thymic independent antigens?
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Commonly made of repeating units (carbohydrates, some polymers, etc.)
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In what case area haptens immunogenic? Antigenic?
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Immunogenic --> Never
Antigenic --> When conjugated to an immunogenic carrier (ex. protein) |
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IMPORTANT: What is an immunological cross reaction?
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The reaction of an antibody with an antigen other than the one that inducted its formation
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