HTHSCI 3I03 Midterm: Adaptive Immunity Study Notes
25 Mar 2015
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Differ by their heavy chains: alpha/beta receptors -- most common, alpha - vj recombination (vaj, beta - vdj recombination, gamma/delta receptors. Detected by cd8+ t cells --> cytotoxic t cells. Detected by cd4+ t cells --> helper t cells. T cells are activated in lymphoid organs by professional apcs. Mhc i: activates cd8 killer t cells: 2 polypeptide chains: alpha chain (3 subunits, polymorphic, hla gene), beta microglobulin, binds peptides 8-10 residues long, derived from intracellular proteins. Mhc ii: activates cd4 helper t cells, which manipulate the local environment using soluble mediators such as cytokines: consists of two homogenous peptide chains, alpha and beta. Subunits are separate domains in the hla gene and each domain is coded by a different exon: binds longer peptides of 15-24 residues derived from extracellular proteins. People must share or recognize the same mhc in order to share tissue, which is rare. Foreign mhc will be recognized as non-self and rejection will occur.
