Autoimmune vitiligo as a roadmap to melanoma therapy

描述(申请人提供)：在自身免疫性白癜风中，黑素细胞被识别黑素细胞分化抗原的细胞毒性T细胞破坏，包括MART-1和gp100。这会导致皮肤和头发逐渐脱色。尽管这种疾病可能会使人虚弱和美观，但黑色素瘤患者非常希望在脱色过程中产生有效的免疫反应。在恶性黑色素瘤中，渗入肿瘤的T细胞经常识别与白癜风有关的相同的分化抗原，然而所建立的抗肿瘤免疫反应很少导致真正的肿瘤消退，如果真的导致了肿瘤消退，这种肿瘤消退也可能伴随着皮肤(白皮病)的进行性脱色。白癜风和黑色素瘤T细胞反应性的这种差异可能是黑色素瘤中对自身抗原反应的T细胞克隆性缺失的结果，而在自身免疫性白癜风中，高亲和力T细胞被异常地引入循环。需要测试的主要假设是，来自活跃脱色患者皮肤的T细胞比来自黑色素瘤肿瘤的T细胞对黑素细胞更具反应性，这种增强的疗效至少部分可以归因于更高亲和力的T细胞受体的表达。为了验证这一假设，T细胞将从任一来源分离、增殖和克隆，鉴定目标抗原(重点是gp100和MART-1)并进行功能分析。来自与gp100或MART-1反应的HLAA*0201限制性克隆的T细胞受体基因将被克隆到逆转录病毒载体中，并在相同的背景下(在Jurkat细胞中)表达，以进一步表征TCR在差异反应中的相对贡献。最后，不同的T细胞亲和力将在体内模型中进行测试。高亲和力T细胞受体基因将在患者PBL中表达，并被导入免疫缺陷小鼠，用来自同一患者的黑色素瘤细胞攻击。将测量肿瘤缩小程度，并对部分组织进行免疫组织学分析。目前的项目将提供对定义对白癜风黑素细胞的有效免疫反应的因子这一紧迫问题的洞察，这在黑色素瘤中是不存在的。重要的是，在逆转录病毒载体中克隆高亲和力T细胞受体可能适合于将其引入患者外周血中治疗恶性黑色素瘤。

DESCRIPTION (provided by applicant): In autoimmune vitiligo, melanocytes are destroyed by cytotoxic T cells that recognize melanocyte differentiation antigens including MART-1 and gp100. This leads to progressive depigmentation of the skin and hair. However debilitating and cosmetically disfiguring this disease may be, the effective immune response underlying the depigmentation process is very desirable for melanoma patients. In malignant melanoma, T cells infiltrating the tumors frequently recognize the same differentiation antigens involved in vitiligo, yet the anti-tumor immune response that is mounted seldom leads to actual tumor regression and if it does, such tumor regression can be accompanied by progressive depigmentation of the skin (leukoderma) as well. This difference among T cell reactivity in vitiligo and melanoma is potentially a consequence of clonal deletion of T cells responding to self-antigens in the case of melanoma, whereas high affinity T cells are aberrantly introduced into the circulation in autoimmune vitiligo. The main hypothesis to be tested is that T cells derived from skin of actively depigmenting patients are more reactive towards melanocytic cells than T cells derived from melanoma tumors, and that such enhanced efficacy can be ascribed at least in part to the expression of higher affinity T cell receptors. To test this hypothesis, T cells will be isolated from either source, propagated and cloned, the target antigens identified (focussing on gp100 and MART-1) and subjected to functional assays. The T cell receptor genes from HLA-A*0201 restricted clones reactive with gp100 or MART-1 will be cloned into retroviral vectors and expressed against the same background (in Jurkat cells) for further characterization of the relative contribution of the TCR to differential reactivity. Finally, differential T cell avidity will be put to the test in an In Vivo model. High affinity T cell receptor genes will be expressed in patient PBL and introduced into immunodeficient mice challenged with melanoma tumor cells from the same patient. Tumor shrinkage will be measured and part of the tissue will be analyzed by immunohistology. The current project will provide insight into the burning question of factors defining an efficient immune response to melanocytic cells in vitiligo that is not encountered in melanoma. Importantly, the cloning of high affinity T cell receptors in retroviral vectors may be suitable for introduction into patient PBL for treatment of malignant melanoma.