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Innate vs Acquired Immunity
- Innate: Primary, nonspecific, immediate, no memory, present at birth
- Acquired: Specific, antigenic, memory, vertebrates only
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Cellular vs humoral immunity
- Further categorization of innate immunity
- Cellular: Macrophages, neutrophils, NK cells
- Humoral: complement, cytokines
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What are the two ways that NK cells induce apoptosis? How do they recognize target cells?
- Injection system (granzyme B)
- Fas ligand on NK cell interacts with Fas protein on target cell surface
- NK cells recognize abnormal MHC I molecules AND bind to the Fc region of bound IgG antibodies
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What are the two ways that NK cells induce apoptosis? How do they recognize target cells?
- MHC I: all cells
- MHC II: APCs
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what is ADCC?
Antibody-dependent cell-mediated cytotoxicity
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Dendritic cell basics
- APC
- In tissues until activated, then travels to lymph nodes
- Possibly most important APC
- Activates naive T cells
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TH cell roles
- Stimulate B-cells (not always required)
- cytokine factory for other immune cells
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3 methods of antibody action
- Bind to cell surface (opsonization)
- Fix complement to cell surface (opsonization)
- Neutralization of substances in plasma
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Hypothesis about anti-D
- Ag clearance: D-coated fetal cells are cleared by mother before triggering response
- Ab-mediated immune supression: Ag-pecific IgG can inhibit Ab responses in immunized animals
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Immunogen vs hapten
- Immunogen: MW > 10,000 daltons
- can illicit immune response
- Hapten: MW < 10,000 daltons
- Must attach to carrier molecule to illicit response
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Structure of Ab molecule
- Two heavy chains (on the inside, full length)
- Two light chains (just the outside, top of the Y)
- Fc region: the constant region at the bottom of the Y
- Fab region: the variable region at the tip of the Y
- Hinge region: disulfide bonds allow flex
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Which Ab is likely to bind complement?
IgM
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What are specific areas of an Antigen that are recognized by the immune system called?
epitopes
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Prozone vs. Postzone effects
- Prozone: excess Ab
- Postzone: excess Ag
- BOTH inhibit agglutinaton
- *ideal ratio is 2 drops plasma to 1 drop 3-5% RBC soln
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3 types of complement activation
- Classic: activated by Ab on cell surface
- Alternative: activated by bacteria, or drugs on cell surface
- Lectin activation: mannose-binding lectin in blood binds to mannose on bacteria
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What are anaphylatoxins?
- C3a and C5a
- Promote release of histamine
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Complement cascade
- b = stays on cell surface
- a = goes to plasma
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