T细胞研究进展.ppt

3.TCR多样性产生的机制 组合造成的多样性： 包括V（D）J基因重排时的随机组合、重排后?-? 及?-?之间随机组合 连接造成的多样性： 胚系基因重排时， V、D、J基因片段连接点可发生核苷酸插入和缺失。 T细胞辅助B细胞 — 40年的研究历史 Multiple signals and steps for the generation of Tfh cells and T-dependent antibody responses Th17的功能 分泌IL-17诱导感染局部的细胞分泌吸引PMN的细胞因子和趋化因子 分泌IL-22 和IL-17 诱导角化细胞表达抗微生物肽（如?-防御素等） Helper T cell differentiation(1) Flexibility and plasticity of helper T cells Thank you! * * * 三类分子、三类细胞、九大行为 * * The answer is CD3. CD3 molecule is made up of g, d, e, z chains. These chains have together 10 ITAMs (immunoreceptor tyrosine-based activation motifs) which are responsible for signal transduction. Figure 6.8. The T-cell receptor complex is made up of antigen-recognition proteins and invariant signaling proteins. The T-cell receptor α:β heterodimer (TCR) recognizes and binds its peptide:MHC ligand, but cannot signal to the cell that antigen has bound. In the functional receptor complex, α:β heterodimers are associated with a complex of four other signaling chains (two , one δ, one γ) collectively called CD3, which are required for the cell-surface expression of the antigen-binding chains and for signaling. The cell-surface receptor complex is also associated with a homodimer of ζ chains, which signal to the interior of the cell upon antigen binding. Each CD3 chain has one ITAM (yellow segment), whereas each ζ chain has three. The transmembrane regions of each chain have either a net positive or negative charge as shown. It is thought that each complete receptor complex contains two α:β heterodimers associated with the six accessory chains shown in the figure, in which case the charges would balance. * 图中显示人免疫球蛋白胚系基因结构：其l和k轻链由V、J、C基因片段编码；重链由V、D、J、C基因片段编码；y代表无功能的假基因。 * * * This is positive selection. If double positive T cells cannot bind to self MHC molecules, they will die. If these T cells recognize peptide/MHCII complex with moderate affinity are positively selected and develop to CD4 single positive T cell, CD8 disappear. If those T cells recognize a