66569
Description
Flashcards by becki_fernandes, updated more than 1 year ago
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Created by becki_fernandes
over 11 years ago
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| Question | Answer |
| After T cells leave the thymus, where do they go? | Travel to secondary lymphoid tissue |
| when do T cells first encounter MHC complexes? | APC's in the lymph node paracortex have MHC complexes |
| which MHC do CD8+ screen for? | MHC I |
| which MHC do CD4 screen for? | MHC II |
| what is meant by the immunological synapse? | transfer of cells from the innate (via MHC) to the adaptive system (via TCR) |
| what do naive T cells require before the TCR can engage? | costimulation |
| how is costimulation achieved? | in the presence of infection, APC's are activated and express CD80 and CD86, + an amplifying signal via CD28 |
| what is the role of of CD8+? | seek out and destroy pathogen in the cytoplasm (virus) |
| what are the 2 roles of CD4? | 1. with TH1 seek out MO to digest bacteria (invesicles) 2. with TH2 seek out B cells to make AB's (pathogen in ECF) |
| explain how CD8+ with MHC I destroys viruses | releases perforin and granzymes, activates the caspase cascade which induces apoptosis via fas/fas ligand pathway and cytotoxic cytokines |
| how do CD4 and TH1 digest bacteria? | MO talk to TH1 via MHC class II, reply by secreting cytokines which provoke other MOs. respiratory burst releasing O2 free radicals, NO and proteases. Lysosomes fuse with endosomes for digestion of pathogen |
| how does Th2 induce AB formation? | B-cells talk to Th2 via MHC II, reply by secreting IL-4 which stimulates the conversion of B cell to plasma cell. secretes AB's and class switching |
| what is the role of TH17? | similar to Th1, proinflammatory, defends epithelial and mucosal surfaces, produces antimicrobials |
| what is the role of regulatory T-cells? | downregulate CD28 signals, negative signal for costimulation (brake) |
| what is the role of natural T-reg's? | produce immunosuppressive cytokine (IL-10) miantain tolerace to self antigens |
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