In Thymic Selection, Peptide Diversity Gives and Takes Away

摘要: Under normal conditions of positive selection, thymocytes expressing different TCRs may be chosen in ways. Some will selected to mature because their react weakly with a single self-peptide/MHC complex on thymus epithelium. This interaction would strong enough rescue the cell from programmed death but not signal by negative selection. In addition, this set any peptide/MHC type must insufficient A fraction these complexes present at low density, and case, selecting peptide similar foreign that activates T cell. Other peptides represented higher ligand relatedness between activating hard recognize (Kersh Allen 1996xKersh, G.J Allen, P.M. Nature. 1996; 380: 495–498CrossRef | PubMed Scopus (273)See all ReferencesKersh 1996).For other cells, it impossible assign selection self-peptide. collection self-peptides (complexed same MHC molecule) provide positively interaction. share easily recognizable common features except as defined strength TCR. Deciphering kind is going hard! At stage we cannot say whether side chains directly contribute energy TCR, or keep out way allowing “touch down” contacts, proposed avoidance model (Schumacher Ploegh 1994xSchumacher, T.N Ploegh, H.L. Immunity. 1994; 1: 721–723Abstract Full Text PDF (58)See ReferencesSchumacher 1994). Both versions gemisch depend involvement specific each The design an experimental system distinguishes two proposals challenge for future.