Allogeneic MiHA Induced Marrow Allograft Resistance

描述（由申请人提供）：随着该领域继续向降低强度调节（RIC）以降低毒性和免疫缺陷的方向发展，更成功的同种异体干细胞/祖细胞移植的一个主要障碍是克服免疫介导的对受体造血植入的抵抗。在之前的资助期间，我们发现了受体对宿主CD8 T细胞介导的供体抗原敏感的抗性途径，而宿主CD8 T细胞不依赖穿孔素、fasl、TNF和其他死亡受体配体。本实验旨在了解来自TN记忆CD8 T （TM）细胞的效应细胞的耐药途径。鉴定和监测免疫优势四聚体+宿主群体将能够对这些细胞进行精确的动力学和区室分析，并提出研究以了解抗原递呈途径和CD4+CD25+宿主T调节细胞对耐药性的调节。实验将确定宿主TN和TM细胞相对于（RIC）和烧蚀条件下的存活、扩增和功能。实验将验证细胞毒性在未致敏受体中T细胞介导的耐药中起重要作用的假设，但在先前对供体抗原致敏的受体中不需要细胞毒性。为了验证T细胞可以直接消除HSC/PC的假设，体外研究将研究来自细胞毒性正常和缺陷受体的T细胞与HSC和MPP富集（LSK FLK-2-）和HSC耗尽的承诺祖细胞富集（LSK FLK-2+）群体共培养。实验将研究stem/PC在其谱系承诺和分化中是否被消除（即通过caspase依赖性凋亡）和/或可以被抑制（即非凋亡）以产生造血集落。总的来说，这些研究将挑战细胞毒性在不同移植环境中发生耐药性的重要性，并产生可能发现非溶解性免疫抑制可能发生在异体造血干细胞/PC的造血移植中。

DESCRIPTION (provided by applicant): As the field continues to move towards reduced intensity conditioning (RIC) to lower toxicity and immune difficiency, a major obstacle toward more successful allogeneic stem/progenitor cell transplantation is overcoming immune mediated resistance to hematopoietic engraftment in the recipient. During the prior grant period we identified a resistance pathway in recipients sensitized to donor antigens mediated by host CD8 T cells independent of perforin, fasl, TNF and other death receptor ligands. Experiments are designed in the present proposal to understand resistance pathways by effector cells derived from naive (TN) memory CD8 T (TM) cells. Identification and monitoring of an immunodominant tetramer+ host population will enable precise kinetic and compartmental analysis of these cells and studies are proposed to understand the antigen presentation pathway and regulation of resistance by CD4+CD25+ host T regulatory cells. Experiments will determine the relative survival, expansion and function of host TN and TM cells with respect to (RIC) and ablative conditioning protocols. Experiments will test the hypothesis that cytotoxicity plays an important role in T cell mediated resistance in unsensitized recipients but is not required for resistance in recipients previously sensitized to donor antigens. To test the hypothesis that T cells can directly eliminate HSC/PC, ex vivo studies will investigate T cells from cytotoxically normal and deficient recipients co-cultured with HSC and MPP enriched, (LSK FLK-2-),and HSC depleted committed progenitor cell enriched (LSK FLK-2+) populations. Experiments will investigate whether stem/PC are eliminated (i.e., via caspase dependent apoptosis) and/or can be suppressed (i.e., non-apoptotically) in their lineage commitment and differentiation to generate hematopoietic colonies. Overall, these studies will challenge the importance of cytotoxicity in resistance occuring in different transplant settings and generate findings which may discover non-lytic immune inhibition can occur against hematopoietic engraftment by allogeneic HSC/PC.