ANTIGEN IMMUNOSUPPRESSION BY KILLER LANGERHANS CELLS

朗格汉斯细胞（LC）通常向T细胞传递激活信号。我们假设，LC基因修饰过表达CD 95 L（Fas配体）称为“杀手”LC，将提供凋亡信号的T细胞抗原特异性相互作用。为了测试这一点，我们将CD 95 L cDNA引入我们的LC系XS 10 - 6（源自A/J小鼠）中，并选择表达丰富的表面CD 95 L的稳定克隆（XS 10-6-CD 95 L）。当用卵清蛋白（OVA）脉冲时，这种杀伤LC克隆通过抗原特异性和CD 95 L依赖性机制在体外触发OVA反应性CD 4 + T细胞的凋亡。OVA脉冲的杀伤LC，当注射到A/J小鼠致敏之前或之后，抑制耳肿胀反应DNFB。重要的是，OVA脉冲的杀伤LC抑制OVA应答，但不抑制对无关抗原HEL的应答，而HEL脉冲的杀伤LC仅抑制HEL应答，建立抗原特异性。我们将定义机制，在新的假设，即杀伤LC抑制不同的免疫反应，通过触发细胞凋亡的推定效应T细胞，识别各自的抗原。具体而言，我们将使用五种建立的动物模型研究杀伤LC的影响：1）迟发型超敏反应：我们将在致敏前后注射OVA脉冲的杀伤细胞LC，研究其对CD 4+效应T细胞和记忆T细胞的影响，以及效应细胞的命运10转基因小鼠的OVA反应性初始CD 4 + T细胞的过继转移），以及杀伤LC与T细胞的细胞毒性相互作用的关键时间（药物诱导的自杀系统）。2)接触性过敏。我们将在致敏之前或之后注射DNFB脉冲的杀伤LC以研究CD 8+效应T细胞和对Th 2样调节性T细胞的影响、杀伤LC与CD 8 + T细胞的相互作用和抗原特异性。3)Th 2偏向的免疫反应。将用OVA吸收的“贴片”对小鼠进行表皮致敏，以产生OVA特异性IgE和IgG 1抗体和特应性皮炎样皮肤病变。我们将注射OVA脉冲的杀伤LC，以研究对Th 2偏置效应和辅助T细胞的影响以及对皮肤病变的“治疗”功效。4)实验性自身免疫性心肌炎。将用心肌肌球蛋白（CM）致敏小鼠以产生自身免疫性心肌炎。我们将注射CM脉冲的杀伤LC，以研究对识别组织特异性自身抗原的CD 4+致病性T细胞的影响，致病性T细胞的命运以及治疗效果和安全性。5)皮肤移植排斥反应。我们将研究杀伤LC和“杀伤LC杂合体”对同种异体反应性CD 4+和CD 8 + T细胞的影响，这些T细胞通常通过“直接”和“间接”途径活化。这些研究将形成用于建立针对炎性皮肤病的全新免疫抑制疗法的框架，该疗法被设计为选择性地消除识别致病性抗原（例如，半抗原、过敏原、自身抗原和同种异体抗原）。

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).