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75 Cards in this Set
- Front
- Back
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what does the very stable structure of the immunoglobulin domain consist of?
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110 amino acids
2 planes of anti-parallel beta-sheets intrachain disulfide bonds non-covalent bonds immunoglobulin fold |
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where does amino acid variation occur?
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hypervariable region of complementarity determining regions
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what does a complementarity determining region consist of?
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combination of H and L
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how many complementarity determining regions are in an antigen binding site of B cells?
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6
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what is the function of the Fab portion of an Ig?
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binds antigen
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what is the purpose of the Fc region of an Ig?
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activates complement receptors
binds to Fc receptors opsonizes bacteria |
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what are the 9 forms of heavy chains in immunoglobulins?
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IgM, IgD, Ig1-4, IgA1-2, IgE
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what are the two forms of light chains?
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kappa
lambda |
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which two heavy chain types have 6 domains in Fc region (versus 4 in others)?
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IgM
IgE |
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which class of immunoglobulin has a pentamer structure?
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IgM
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which class of immunoglobulin has a dimer structure?
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IgA (in secretions)
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what immunoglobulin has the longest half life? what is the half life?
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IgG
21 days |
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what two immunoglobulins are found on the surface of all mature B cells (without isotype switching)?
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IgG
IgD |
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what is the immunoglobulin found in mucous membranes that prevents attachment of organisms?
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IgA
(mucosal immunity) |
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which immunoglobulin is involved in allergic reactions?
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IgE
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which immunoglobulin is responsible for helping to expel parasites?
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IgE
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which immunoglobulins are particularly good at neutralization?
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IgG1-4
IgA |
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what immunoglobulin is particularly good at opsonizing pathogens?
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IgG1
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which immunoglobulins are useful for sensitizing a cell for killing by NK cells?
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IgG1
IgG3 |
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what two immunoglobulins are particularly good at activating complement?
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IgM
IgG3 |
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what immunoglobulin is capable of transport across epithelium?
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IgA
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which immunoglobulin is best at transport across placenta?
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IgG1
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what immunoglobulins diffuse into extravascular sites?
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IgG1-4
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what do antibodies need to generate a repertoire?
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can bind to any/all possible molecules
each has a unique specificity and affinity |
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where are the variations displayed in immunoglobulins?
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V regions, via somatic recombination
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where is additional diversity displayed?
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in recombination of V region with J and D segments
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what two proteins are specific to lymphocytes and are required for recombination?
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Rag-1 and Rag-2
(Recombinase Activating Gene) |
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what is the job of the recombinase activating gene?
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bring V, D, and J chains together
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what is the first recombination event in light chains?
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V portion attaches with J portion
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what is the second event in recombination of light chains?
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primary transcript of RNA is made
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what is the first step in recombination of heavy chains?
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D region is spliced with J region
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what is the second step in recombination of heavy chains?
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DJ region is spliced with V region
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when is C region recombined adjacent to VDJ region?
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not until exons are removed during mRNA splicing
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what is junctional diversity?
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sloppy recombination resulting in variations in DNA sequence
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what does terminal nucleotidyl transferase (TdT) do?
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add bases to 3' end of DNA
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what is the order of isotypes in the heavy chain DNA?
where are the isotypes located? |
mu, delta, gamma3, gamma1, alpha1, gamma2, gamma4, epsilon, alpha2
isotypes are found in the C regions of DNA |
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what targets the switch regions to switch isotypes?
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AID
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where do loops for isotype switching begin and end in a recombining heavy chain?
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two switching regions are brought together after having been nicked (switching region of current isotype and switching region of isotype to switch to)
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what cytokine is used to convert multipotent progenitor cell to a common lymphoid progenitor as well as certain points in the maturation of B cells?
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IL-7
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what immunoglobulin is expressed by B cells when they leave marrow?
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IgM
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where do B cells finish maturation?
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secondary lymphoid organ
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what happens if VDJ rearrangement is unsuccessful?
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heavy chain will not be expressed, so the protein will not be produced
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what proteins anchor immunoglobulins into the cell membrane?
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Igalpha
Igbeta |
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what is the surrogate light chain?
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protein whose sole purpose is to associate with the heavy chain and bring it to surface to signal that heavy chain has been successfully rearranged (VpreB, lambda5)
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what signalling molecule is required for proliferation of the B cell?
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tyrosine kinase BTK
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which light chain is rearranged first?
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kappa light chain, followed by lambda
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when is the first checkpoint for B cells?
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pre-B-cell receptor, consisting of VpreB, lambda5, and heavy chains
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what happens in pro-B cell?
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commits to B cell lineage
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what does the first checkpoint in B lymphocyte maturation check for?
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functional heavy chains
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what does the second checkpoint in B lymphocyte maturation check for?
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functional light chains
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when are self-reactive receptors checked for and eliminated?
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second checkpoint
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what gene rearrangement occurs in pro-B cell?
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H-chain gene rearrangement
D-J rearrangements on both chromosomes |
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what rearrangement is occuring in Late pro-B cells?
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H-chain gene rearrangement
V-DJ on one chromosome at a time until both are exhausted (if viable heavy chain can't be found) |
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what rearrangement occurs in pre-B cells?
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L-chain rearrangement
kappa gene on chromosome 1 -> kappa gene on chromosome 2 -> lambda gene on chromosome 1 -> lambda gene on chromosome 2 -> cell death if a viable light chain is not formed |
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what is expressed on immature B cells?
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either mu:kappa immunoglobulin or mu:lambda immunoglobulin
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how many chances are there to create a viable heavy chain?
how many chances are there to create a viable light chain? |
2 chances for a heavy chain
4 chances for a light chain |
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what do mature B cells express?
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single binding specificity from heavy chain and light chain protein (IgM and IgD have same binding site)
MHC class II CR1, CR2 CD19 |
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what is the name for the process by which both IgM and IgD are expressed by mature B cells?
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alternative splicing of RNA
(process by which Cmu or Cdelta can be spliced into the heavy chain) |
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what is positive selection for B cells in bone marrow?
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make sure B lymphocytes bind to MHC class II
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what is negative selection for B cells in bone marrow?
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make sure B lymphocytes don't bind to complex of MHC class II with self protein
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what are electrostatic forces?
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attraction between opposite charges
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what are hydrogen bonds?
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hydrogen shared between electronegative atoms (N, O)
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what are Van der Waals forces?
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fluctuations in electron clouds around molecules oppositely polarize neighboring atoms
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what are hydrophobic forces?
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hydrophobic groups interact unfavorably with water and tend to pack together to exclude water molecules
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what is called affinity?
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Keq
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what is ELISA?
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enzyme linked immunosorbent assay
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how is ELISA performed?
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adsorb known antigen to plastic well, and add serum to be tested to the well, if the serum contains the antibody of interest it will bind the antigen, and then wash with antibody (which reacts with any human immunoglobulins) that has been coupled to peroxidase, add chromogen which changes color when reacted on by peroxidase
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how is RIA different from ELISA?
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the anti human gamma globulin antibody is radiolabeled rather than marked with peroxidase
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In what test is a virus dissociated in SDS, put in SDS page, transferred to nitrocellulose and overlayed with antiserum, and then finally detected bound to antibody with enzyme linked anti IgG
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Western Blot
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how does flow cytometry work?
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cells with certain cell surface proteins are mixed with fluorescence tagged antibodies that are passed through a laser in droplets (each with one cell) and fluoresce on contact with the laser; antibodies specific for different cell surface proteins fluoresce different wavelengths so that multiple proteins can be assayed
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what is indirect immunofluorescence?
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antigen bound by antibody with generalized antigen, which is then bound by secondary antibody with fluorescent green marker under UV light
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what is immunoprecipitation?
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process of using specific antibody to precipitate an antigen protein of interest from solution
(uses constant amount of antibody and increasing amount of antigen) |
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what is the difference between precipitation and aglutination?
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agglutination brings large insoluble things (e.g. bacteria) together
precipitation draws small soluble things (e.g. molecules and proteins) out of solution |
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what is an antibody titer?
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the greatest dilution of serum (antibodies) that is still positive for assay
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which serum contains the most antibody for this antigen?
Serum A-Titer: 1/20 Serum B-Titer: 1/400 |
Serum B-titer means that 1 mL of serum diluted into 400mL can still detect the antigen whereas 1mL can only be diluted into 20mL in serum A (while still being able to detect antigen)
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