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50 Cards in this Set
- Front
- Back
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what is tolerance?
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unresponsiveness to an antigen
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what is central tolerance?
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immature lymphocytes recognizing self antigens in bone or thymus
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what is peripheral tolerance?
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mature lymphocytes encountering self antigens in the peripheral lymph organs
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what is CD3?
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a polypeptide that is part of all T cells TCR
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what is CD4?
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a polypeptide that is part of TCR on T helper cells
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what is CD8?
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a polypeptide that is part of TCR on cytotoxic T cells
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what is CD28?
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a receptor on T cells
for costimulation with B7 on B cells |
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what is MHC?
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a molecule on APCs that holds and presents the antigen
two types: I & II |
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what can CD8 bind to?
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MHCI
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what can CD4 bind to?
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MHCII
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what is normal ratio of T helper: T cytotoxic?
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2:1
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what is the Th1 response?
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cytokine release for inflammation & activates T cells and macrophages (to lyse with lysosomes)
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what is the Th2 response?
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activates B cells and immune responses that depend on antibodies
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what is the Tc response?
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recognize and eliminate altered self cells
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how does B cell anergy happen in the periphery?
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autoreactive B cell encounters antigen, downregulates IgM, encounters T cell for antigen, Fas meets Fas, apoptosis
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where is Fas ligand normally produced?
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on T cells
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what happens if T cells express Fas and not Fas ligand?
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they are stimulated to produce Fas ligand, it binds to Fas, and apoptosis
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what is a role of regulatory T cells?
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preventing autoimmune disease
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what is autoimmunity?
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immune response against self antigens (antibodies, effector T cells, and their products are all responsible)
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what are hormonal reasons for autoimmune disease?
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variation between sexes
improvement of condition during pregnancy |
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what are three mechanisms of autoimmune pathology?
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direct antibody mediated effects
T cell mediated effects immune complex mediated effects |
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what are 4 ways autoimmune diseases are initiated?
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1. escape of autoreactive clones
2. cross reactive antigens 3. lack of regulatory T cells 4. sequestered antigen |
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how is diagnosis of autoimmune diseases made?
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symptoms and detection of antibodies
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how are antibodies to tissue antigens detected?
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immunofluorescence
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how are antibodies to soluble antigens detected?
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ELISA, radioimmunoassay
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what is the goal of Tx for autoimmune disease?
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1. reduce symptoms
2. control autoimmune response 3. maintain body's ability to fight infection |
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how are B cells distinguished from other lymphocytes?
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display membrane-bound immunoglobulin molecules
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what else is expressed on B cell membranes?
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class II MHC
FcgammaRII (receptor for IgG) B7 (costimulation: CD28 on T cells) CD40 (costimulation: CD40ligand on T cells) |
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what do plasma cells do?
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they secrete antibody (they have less membrane-bound antibody than B cells)
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where is MHC I displayed?
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all somatic cells
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where is MHC II displayed?
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professional antigen presenting cells
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what type of antigens does MHC I present?
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endogenous
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what type of antigens does MHC II present?
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exogenous
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what cytokines do Th1 produce for cell-mediated immunity?
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IFN-gamma, IL-2, TNF
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what cytokines does Th2 release for humoral immunity?
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IL-4, IL-5, IL-10
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what is the role of IFN-gamma and CD40ligand?
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activate macrophages to destroy engulfed bacteria
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what is the role of Fas-ligand and TNF-beta?
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kills chronically infected cells, releasing bacteria to be killed by fresh macrophages
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what is the role of IL-2?
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induces T cell proliferation, increasing number of effector T cells
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what is the role of TNF-alpha and TNF-beta?
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activates endothelium to induce macrophage binding and exit from blood vessel at site of infection
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what is the role of MCP-1?
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causes macrophages to accumulate at site of infection
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what is the role of IL-3 and GM-CSF?
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induces macrophage differentiation in the bone marrow
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what is class (isotype) switching?
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the constant portion of an antibody changes while the variable portion remains the same
(retains affinity for the same antigen) |
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what factors (incl. cytokines) are needed for class switching?
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IL-4, IFN-gamma, TNF-beta
CD40 ligand |
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what is somatic hypermutation?
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programmed mutation of genes for variable regions of immunoglobins.
allows immune system to adapt to foreign elements. |
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what about IgG?
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most abundant in serum
monomer can cross placenta neutralizes Ag 1/2 life of 3 weeks |
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what about IgM?
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pentamer
poor diffusion activates complement primary response to antigen |
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what about IgA?
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in secretions (breast milk, saliva...)
dimer |
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what about IgE?
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in allergic response
induces mast cell degranulation |
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what is myasthenia gravis?
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an autoimmune disease where antibodies exist that bind the ACh receptors, blocking neuromuscular transmission
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what cytokines contribute to septic shock?
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IL-1, IL-6, IL-8, TNF
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