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| Question | Answer |
| adaptive immunity triggered when | infection eludes or overwhelms innate- there is antigen threshold |
| how does adaptive arm of immune response kick in | dendritic cells present antigen, antigen specific effector T cells & antibody secreting B cells by clonal expression |
| what characterises resolution of infection | clearance of extracellular infectious particles by opsonisation and phagocytes |
| 4 steps of innate reaction to pathogen | 1. macrophages and DC produce/secrete cytokines/chemokines, 2. effector cells recruited to site, 3. neutrophils arrive(then macrophages), 4. acute phase response activated |
| major cells of innate | phagocytes (macrophages and pmns), NK cells, mast cells and basophils, dendritic cells |
| neutrohils | short half life, highly phagocytic, main function to patrol bloodstream |
| surface receptors on neutrophils | TLR, mannose , complement , FC, chemokine |
| opsonisation | making a microbe easier to phagocytise by coating with molecules including C3b |
| surface receptors on monocytes/macrophages | TLRs, mannose, FC, complement, MHC I & II, adhesion |
| NK cells | larger than normal lymphocytes and have dense granules. main function to kill virus infected and tumour cells. work like CTCs re perforin |
| surface receptors on NK cells | KIRs, KARs, FC, adhesion |
| how are NK cells activated | IL-2. when activated release INFy |
| mast cells + basophils | large granules |
| step one: mo+dc produce/secrete cytokines | starts the inflammation process |
| step two: effector cells recruited | extravasation |
| step 3: neutrophils arrive | triggered to release granules. MO arrive second |
| basophils + mast cells release granules when stimulated by: | binding C3a and C5a, binding to lectin, some drugs, binding of allergens to their IgE |
| step four: acute phase response activated | changes the blood protein mix |
| dendritic cells | primary interface between innate and adaptive. process antigens and present to T cells. recognise antigens through PRRs. have MHC II |
| recognition of microbes by innate immune system: receptor list (5) | 1. PRRs , 2. TLRs, 3. NOD like , 4. mannose, 5. scavenger |
| what are acute phase proteins? | plasma proteins that maximise complement activation and opsonisation. include C-reactive protein and MBL |
| what are cytokines | small molecules that signal between cells. primarily produced by leukocytes. |
| what are interleukins | cytokines- ability to communicate between leukocytes. critical to immune defense |
| interferons | produced in response to viral infections. increases antigen presentation, activates NK cells and phagocytes |
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