71421
| Pregunta | Respuesta |
| class II antigen procesessing steps | 1. pathogen endocytosed into acidified vesicle, 2. endopeptidases break to 10-20 aa, 3. fused with MHC II in ER, 4. displayed |
| steps of endogenous processing | 1. pathogen enters cytosol, is modified and sent to proteasome, 2. processed to 8-10 aa, 3. sent to ER, 4. combined with newly formed MHC I, 5. displayed on cell surface |
| MHC molecules are expressed | codominantly |
| three professional antigen presenting cells | 1. dendritic cells (DC), 2. macrophages, 3. B lymphocytes |
| MHC-Major histocompatibility complex- two classes | Class I- all nucleated cells. Class II- antigen presenting cells, B lymphocytes, activated T lymphocytes |
| APCs | antigen presenting cells |
| antigens displayed on MHC are... | linear as T cell receptors only recognise linear shapes |
| what does class I MHC activate | CD8+ cytotoxic T cells |
| what does class II MHC activate | CD4+ helper cells |
| three major types of mature T cells | 1. Helper T cells (Th)= CD4+. 2 cytotoxic T cells (Tc)= CD8+. 3. Supressor T cells (Ts) = CD4+CD25+foxP3+ |
| T cells cannot recognise or bind to... | ...microbes or thier unprocessed peptides |
| MHC molecules are | glycoproteins |
| Th1 cells enhance | cell mediated immunity |
| Th2 cells enhance | B cells to produce antibodies, activate eosinophils, IgM and IgE |
| Tc cells destroy | virally modified or foreign cells |
| Ts cells inhibit | activation of T and B cells |
| Class I pathway | endogenous |
| Class I antigen processing | mostly from viruses- degraded to 8-10 peptides, in proteasomes (factories) |
| Class II pathway | exogenous |
| Class II processing | molecules are produced within ER, outcome is fused vesicles being displayed |
| structure of MHC I | one legged molecule with 2 chains- an alpha with 3 domains-alpha 1,2,3 and a tiny beta2 microglobulin. The outer domains form a binding groove. |
| MHC II molecule structure | two legged molecule with 4 domains: alpha 1 & 2 and beta 1 & 2. binding groove formed by 2 outer domains. |
| MHC aka | HLA |
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