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21 Cards in this Set
- Front
- Back
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What are the 4 polypeptide chains in an antibody?
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2 identical heavy chains
2 identical light chains connected by disulfide bonds and noncovalent interations |
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What are the different segments of the heavy chain gene and how do they relate to the final polypeptide?
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VDJ--variable region which is the antigen binding site on the antibody specifically on the CDR
C is the constant region and it determines the isotype of the antibody. |
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Ability to bind to Fc receptors can be changed by
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changing the heavy chain constant region
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what are the different light chain segments and how do they relate to the final polypeptide
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VJ and C
kappa and lambda which can bind to heavy chain |
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describe how the RAG enzymes function
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RAG binds to RSS to begin DNA recombination. The DNA sequence is the substrate. RAG combines V D and J regions to make a hairpin loop and cuts between them to form a terminal end. DNA repair makes random segments of DNA giving new variations in DNA to encode new immunoglobulins and TCRs
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IgM is on
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heavy and light chains
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mu and gamma are only heavy but mu eventually encodes
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IgM
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The ability of an antibody to perform a specific effector function is often due to an _____
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antibody binding to Fc receptor
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why do people that lack RAG also lack B cells and T cells
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RAG is the only enzyme that does DNA recombination to make immunoglobulins and TCRs. Without this enzyme they cannot bind to the antigen and they eventually die.
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Stages of B cell development and changes in heavy and light chains
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lymphoid stem cells-->pro-->pre-->immature-->naive-->mature
pro gets d and j, pre gets vdj immature gets vj immature gets IgM |
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indicate the region of the antibody that changes during isotype switching
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switch region--2-3 kb upstream of the constant heavy chain region. These regions are large but composed of multiple short subunits.
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During isotype switching __ act as switch factors and ______
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cytokines
play major roles in determining the particular immunoglobulin expressed. |
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Isotype switching depends on
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interplay of 4 elements: switch region, switch recombinase, cytokine signaling, AID
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Indicate the region of the antibody that changes during affinity maturation
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variable sequences of heavy and light chains
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affinity maturation is the process by which _____
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B cells produce antibodies with increased affinity for antigens during the course of an immune response. with repeated exposure to the same antigen the B cells produce antibodies with successively greater affinities.
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When B cells become activated during affinity maturation the _______
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AID enzyme increases the affinity of variable regions to antigens by directly putting mutations into their variable sequence.
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What are primary and secondary follicles?
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Primary follicles have not yet been activated by an antigen and house dendritic cells and small resting B cells. Secondary follicles house activated B cells and are more likely to have IgG, IgA or IgE on their surface than B cells in primary follicles. The germinal center is in the secondary follicle.
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Plasma cells are secreted by the ___
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medulla
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B cells are in the ___ of the lymph node
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cortex
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Why is Fcgr not called FcIgG?
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IgG refers to both heavy and light chains of the antibody but the receptor only binds to the constant part of the heavy chain on the gamma subtype.
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Describe the effector function of the five different isotypes
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IgG--IFN-gamma, most abundant in serum, opsonizes antigens
IgM is on naive B cells, secreted by plasma cells IgA is in mucus, tears and breast milk, TGF-beta IgG is at high levels in serum of patients with allergies, IL-4, mediates hypersensitivity reactions IgD together with IgM is the major membrane bound immunoglobulin expressed on mature B cells |
