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19 Cards in this Set
- Front
- Back
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What is the ARM of B cells? Where can they be found?
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ARM of B Cells = Immunoglobulins
Membrane bound on B-cell surface = B cell receptor Ig of same antigen specificity secreted as Ab by plasma cells OR terminally differentiated B cells |
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What is the main effector function of B cells?
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Secretion of antibodies
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What is the ARM of T cells? Where can they be found?
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ARM of T Cells = T cell receptors found on membrane surface
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What are the antigen recognizing portions of BCR's and TCR's?
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Variable regions
(conserved portions are Constant Regions) |
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What are the three effector functions of antibodies?
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1) Fixation of complement: an immune response in which an antigen-antibody combination inactivates a complement (so it is unavailable to participate in a second antigen-antibody combination)
2) Binding to various cell types (Phags, lymphs, platelets, mast cells, basophils) which activates them to perform some function 3) Bind to receptors on placental trophoblasts, resulting in TRANSFER of Ig across placenta (provides immunity to fetus and newborn) |
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What type of cells produce antibodies?
What type of antigens (native/processed) do antibodies recognize? What chains comprise antibodies? Which region binds antigen? |
B Cells produce Ab's
Antibodies bind native antigens Ab's consist of heavy and light chain with variable and constant regions (H2L2); variable region (V part of Ab) binds Ag (Gene coding for heavy chain is not same as gene coding for light chain) |
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What is the purpose of the Fc tail?
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Fc tail, if exposed, has Fc receptor complement binding sites that allow for opsonization
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For each of the 5 major isotypes of antibodies:
Structure (monomer, dimer, etc) Functions Which Ig is most abundant in serum? |
IgG: monomer; carries out all fns of Ig molecs, MOST ABUNDANT in serum; can cross PLACENTA; ESSENTIAL to humoral response
IgA: monomer; mucosal; found in secretions (tears, saliva, colostrum--breast milk first few days, mucus) IgM: pentamer (can be monomer); first Ig made by fetus and first Ig produced during primary immune response; good complement fixing Ig (binds Fc) because of pentameric structure igE: monomer; allergic rxns, parasites |
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What are the co-receptors of TCR's?
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CD 4 or CD 8
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Role of CD3 molecules?
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Form complex with TCR in mature T cells
CD3 molecules are required for signal transduction for dx/dy, clonal expansion, etc. |
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Describe the molecular structure of TCR's.
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Disulfide-linked heterodimer: either alpha-beta (95%) or gamma-delta (5%) ; T cells either express one or the other, NEVER BOTH
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Role of complimentarity determining regions?
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CDRs 1-3 = hypervariable regions of TCR and confer specificity for Ag recognition
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Role of Integrin Cell Adhesion Molecules on T Cells?
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ICAMs on T cell (LFA-1,2) interact with ligands on APC surface (ICAM-1, LFA-3) to stabilize TCR and peptides
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Role of CD28?
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Provides costimulatory signal for T-cell response
So do CD80,40,40L |
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Beginning with CD4- CD8- cells in the bone marrow, describe the steps required for the development of a DIVERSE repertoire of MATURE T cells. List all enzymes required!
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Maturity:
CD4-CD8- cells migrate to thymus Thymocytes with ability to bind self-MHC expressed by epithelial cells (of cortical thymus) are retained [POSITIVE SELECTION]; those that don't undergo apoptosis Thymocytes with high affinity receptors for self-MHC molecs alone or self-antigen presented by self-MHC by DC's and macs are killed [NEGATIVE SELECTION]; results in self tolerance These CD4+CD8+ cells then become mature CD4+ or CD8+ DIVERSITY: Via Somatic Recombination--in thymus, Diversity Region (Gene) is joined to J Region, DJ Region is joined to Variable Region; this is all facilitated by recombinases (RAG1/2) VJD = genes encoding TCR |
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CD4+CD8+ exhibiting weak recognition of class II MHC + peptide results in ______________
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Mature CD4+ T Cell
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CD4+CD8+ exhibiting weak recognition of class I MHC + peptide results in ______________
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Mature CD8+ T Cell
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CD4+CD8+ exhibiting no recognition of class II MHC + peptide results in ______________
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Apoptosis (failure of positive selection--death by neglect)
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CD4+CD8+ exhibiting strong recognition of class II MHC + peptide results in ______________
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Apoptosis via negative selection
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