ANTIGEN IMMUNOSUPPRESSION BY KILLER LANGERHANS CELLS

朗格汉斯细胞（LC）通常将激活信号传递给T细胞。我们假设，经过基因修饰过表达CD95L （Fas配体）的LC被称为“杀手”LC，将通过抗原特异性相互作用向T细胞传递凋亡信号。为了验证这一点，我们将CD95L cDNA引入我们的LC系XS106（来源于A/J小鼠），并选择了一个表达丰富表面CD95L的稳定克隆（XS 10-6-CD95L）。这个杀伤LC克隆，当卵清蛋白（OVA）脉冲时，通过抗原特异性和cd95l依赖的机制，在体外触发OVA反应性CD4+ T细胞的凋亡。在致敏前或致敏后给A/J小鼠注射ova脉冲杀伤LC，可抑制DNFB对耳肿胀的反应。重要的是，OVA-脉冲杀伤LC抑制OVA应答，但不抑制无关抗原HEL应答，而HEL-脉冲杀伤LC仅抑制HEL应答，建立抗原特异性。在新的假设下，我们将定义机制，即杀伤LC通过触发识别相应抗原的假定效应T细胞的凋亡来抑制多种免疫反应。具体来说,我们将研究使用five-established杀手LC动物模型的影响:1)延迟类型超敏反应:我们将注入卵子之前或之后——脉冲杀手LC致敏研究CD4 + T细胞影响的影响和记忆T细胞,命运的效应细胞(CD4 + T细胞过继转移OVA-reactive,天真D011.10转基因老鼠),和细胞毒性的关键时机交互杀手LC的T细胞(drug-inducible自杀系统)。2)接触性过敏。我们将在致敏前后注射dnfb脉冲杀伤LC，以研究CD8+效应T细胞和th2样调节性T细胞的影响、杀伤LC与CD8+ T细胞的相互作用和抗原特异性。3) th2偏向性免疫反应。小鼠将被表皮致敏，用ova吸收的“贴片”产生ova特异性IgE和IgG1抗体和特应性皮炎样皮肤病变。我们将注射ova脉冲杀伤LC，研究其对th2偏置效应T细胞和辅助T细胞的影响以及对皮肤病变的“治疗”效果。实验性自身免疫性心肌炎。心肌球蛋白（CM）致敏小鼠产生自身免疫性心肌炎。我们将注射cm脉冲杀伤LC，研究其对识别组织特异性自身抗原的CD4+致病性T细胞的影响，致病T细胞的命运，以及治疗的疗效和安全性。5)皮肤移植排斥反应。我们将研究杀伤LC和“杀伤LC杂交体”对同种异体反应性CD4+和CD8+ T细胞的影响，这两种细胞通常通过“直接”和“间接”途径激活。这些研究将为建立一种全新的炎症性皮肤病免疫抑制疗法奠定基础，这种疗法旨在选择性地消除识别致病性抗原（如半抗原、过敏原、自身抗原和同种异体抗原）的效应T细胞。

Langerhans cells (LC) ordinarily deliver activation signals to T cells. We hypothesized that LC genetically modified to over-express CD95L (Fas ligand) termed "killer" LC, would deliver apoptotic signals to T cells upon antigen-specific interaction. To test this, we introduced CD95L cDNA into our LC line XS106 (derived from A/J mice) and selected a stable clone (XS 10-6-CD95L) that expressed abundant surface CD95L. This killer LC clone, when pulsed with ovalbumin (OVA), triggered apoptosis of OVA-reactive CD4+ T cells in vitro by an antigen-specific and CD95L-dependent mechanism. OVA-pulsed killer LC, when injected into A/J mice before or after sensitization, suppressed ear swelling responses to DNFB. Importantly, OVA-pulsed killer LC suppressed OVA responses, but not responses to the irrelevant antigen HEL, whereas HEL- pulsed killer LC inhibited only the HEL responses, establishing antigen- specificity. We will define mechanisms, under the new hypothesis that killer LC suppress diverse immunological responses by triggering apoptosis of putative effector T cells that recognize respective antigens. Specifically, we will study the impact of killer LC using five-established animal models: 1) Delayed type hypersensitivity: We will inject OVA- pulsed killer LC before or after sensitization to study the impact of CD4+ effect T cells and memory T cells, the fate of effector cells (adoptive transfer of OVA-reactive, naive CD4+ T cells from the D011.10 transgenic mice), and the critical timing for cytotoxic interaction of killer LC with T cells (drug-inducible suicide system). 2) Contact hypersensitivity. We will inject DNFB-pulsed killer LC before or after sensitization to study the impact of CD8+ effector T cells and on Th2-like regulatory T cells, killer LC interaction with CD8+ T cells and antigen- specificity. 3) Th2-biased immune responses. Mice will be sensitized epicutaneously with an OVA-absorbed "patch" to produce OVA-specific IgE and IgG1 antibodies and atopic dermatitis-like skin lesions. We will inject OVA-pulsed killer LC to study the impact on Th2-biased effector and helper T cells and "therapeutic" efficacy for skin lesions. 4) Experimental autoimmune myocarditis. Mice will be sensitized with cardiac myosin (CM) to produce autoimmune myocarditis. We will inject CM-pulsed killer LC to study the impact on CD4+ pathogenic T cells that recognize tissue-specific autoantigen, the fate of pathogenic T cells, and therapeutic efficacy and safety. 5) Skin graft rejection. We will study the impact of killer LC and "killer LC hybrids" on allo-reactive CD4+ and CD8+ T cells, which are ordinary activated via "direct" and "indirect" pathways. These studies will form the framework for establishing an entirely new immunosuppressive therapy for inflammatory skin diseases, the therapy designed to eliminate selectively the effector T cells that recognize pathogenic antigens (e.g., haptens, allergens, autoantigens, and alloantigens).