61286
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 |
| where does MHC I present antigens from? | the intracellular fluid e.g. viruses |
| where does MHC II present antigen from? | the extracellular fluid e.g. bacteria |
| state the structure of a MHC I | alpha peptide only, 3 genes A,B,C |
| state the structure of a MHC II | alpha and beta peptides, 3 genes - DR,DP,DQ |
| where does the antigen sit on a MHC molecule? | peptide binding groove |
| which cells express MHC I? | all nucleated cells |
| explain the MHC I pathway (6 steps) | 1. proteosomal degradation - virus proetins broken to peptides 2. peptides transferred to ER by TAP 3. MHC I synthesised and assembled in ER using chaperones 4. peptides loaded onto empty MHC 5. complex transported via golgi to surface 6. can now be detected by CD8+ t cells |
| which cells express MHC II? | only APC's |
| explain the MHC II pathway ( 6 steps) | 1. MHC II is synthesised in the ER, binding of cytoplasmic fragments is prevented (CLIP in PBG) 2. foreign antign is endocytosed and lysosomes fuse with primary endosomes 3. antigen is digested to peptide 4. MHC and endocytic pahways merge (CLIP replaced) 5. complex transported to cell surface . can be detected by CD4+ t cells |
| what are dendritic cells and what do they present to? | professional APC's that present antigen to naive T cells which stimulates a response in secondary lymphoid tissues |
| what do macrophages and B cells present antigen to? | Th1 or TH2 in reaction to an infection |
| explain how immature dendritic cells become interdigitating dendritic cells | immature DCs migrate to epithelial surfaces and encounter antigen, then migrate to lymph nodes and process antigen, then take up residence in LN paracortex as IDC and present the antigen to T cells |
| name 3 facts about MHC genes | polygenic, co-dominantly expressed and polymorphic |
| what does a lack of diversity in MHC lead to? | susceptibilty to infection, reduced response to vaccination, increased risk of autoimmune diseases |
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