Fas Regulates T Cell Development/Function in Lpr Mice

描述(由申请人提供)：尽管13年前IPR基因被确认为死亡受体基因fas的突变，但积累的CD4+、CD8+和不寻常的CD4-CD8-(CD4-8-)TCRab+T淋巴细胞的来源仍然是一个谜。自身免疫性IPR小鼠在用抗原肽、超抗原或感染剂激活后，胸腺阴性选择或外周T细胞缺失没有明显的缺陷。 这项资助假设IPR小鼠的腺病源于T细胞不受限制的内稳态增殖。这与观察到的IPR小鼠即使在无抗原环境中也会发生腺病的观察是一致的。在RAG1-/-小鼠体内平衡增殖过程中，供者的IPR T细胞比野生型T细胞积累的数量多得多，并产生了CD4-8-TGRab+细胞。由于动态平衡增殖是由低亲和力TCR/自身MHC多肽信号驱动的，这表明Fas的功能是消除从自身抗原接收低亲和力信号的T细胞。该模型还预测，那些接受低强度TCR信号的CD8+T细胞将成为CD4-8-TCRab+。四个目标是： 目的1确定CD8+T细胞与多肽/MHC发生低亲和力或低亲和力TCR相互作用是否优先产生CD4-8-TCRab+T细胞。首先，TCR/MHC亲和力将通过将多克隆CD8+细胞(野生型、IPR或Bim-/-)转移到SCID、B2M-/-SCID和TAP-/-SCID小鼠中而降低。第二部分将通过将OVA反应的OT-I T细胞转移到TAP-/-RAG-/-小鼠，表达不同OVA多肽对OT-I TCR的不同亲和力，来改变TCR/MHC的亲和力。 目的2通过固定抗原(H-Y)和用抗H-Y TCRb(H-Yb)T细胞(野生型、IPR或Bim-/-)改变TCR并监测低亲和力四聚体+细胞与高亲和力克隆型+细胞的存在来解决同样的问题。 目的3研究Fas如何向树突状细胞发出信号，以实现对体内平衡增殖至关重要的效应器功能。 目的4检测动态平衡增殖是否增加自身免疫T细胞的频率/功能。 化疗、放疗和HIV感染后的淋巴细胞减少可引发自身免疫状况。因此，体内平衡增殖的调控是自身免疫机制的核心。

DESCRIPTION (provided by applicant): Although the Ipr genotype was identified as a mutation in the death receptor gene, fas, 13 years ago, the source of the accumulating CD4+, CD8+, and unusual CD4-CD8- (CD4-8-) TCRab+ T lymphocytes remains an enigma. Autoimmune Ipr mice manifest no significant defect in thymic negative selection or peripheral T cell deletion following activation with antigenic peptides, superantigens, or infectious agents. This grant hypothesizes that the adenopathy of Ipr mice originates from unrestrained homeostatic proliferation of T cells. This is consistent with the observation that Ipr mice develop adenopathy even in an antigen-free environment. During homeostatic proliferation in RAG1-/- mice, donor Ipr T cells accumulate to much greater numbers than wild-type T cells, and give rise to CD4-8- TGRab+ cells. Since homeostatic proliferation is driven by low affinity TCR/self-MHC-peptide signals, this suggests that the function of Fas is to eliminate T cells receiving low affinity signals from self-antigens. This model also predicts that those CD8+ T cells receiving low intensity TCR signals will become CD4-8- TCRab+. The four aims are: Aim 1 will determine whether CD8+ T cells that make low avidity or low affinity TCR interactions with peptide/MHC preferentially give rise to CD4-8- TCRab+ T cells. First, TCR/MHC avidity will be decreased by transferring polyclonal CD8+ cells (wild-type, Ipr, or Bim-/-) into scid, b2m-/-scid, and TAP-/-scid mice. The second part will vary TCR/MHC affinity using Ova-responsive OT-I T cells transferred to TAP-/-RAG-/- mice expressing different Ova peptides of varying affinity for the OT-I TCR. Aim 2 approaches the same question by fixing the antigen (H-Y) and varying the TCR using anti-H-Y TCRb (H-Yb) T cells (wild-type, Ipr, or Bim-/-) and monitoring the presence of low affinity tetramer+ cells versus high affinity clonotype+ cells. Aim 3 examines how Fas can positively signal dendritic cells for effector functions that are important for homeostatic proliferation. Aim 4 tests whether homeostatic proliferation increases the frequency/functional of autoimmune T cells. Lymphopenic conditions following chemotherapy, irradiation, and HIV infection can provoke autoimmune conditions. Hence, the regulation of homeostatic proliferation is central to autoimmune mechanisms.