CHARACTERISTICS OF T CELLS MEDIATING TUMOR IMMUNOTHERAPY

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DESCRIPTION: (Applicant's Abstract) The adoptive transfer of tumor-reactive T lymphocytes mediates regression of established malignancies. In animal models, tumor-draining lymph nodes (LN) are a rich source of sensitized T cells that can be activated ex vivo to acquire effector function. In this application the generation of tumor-sensitized T lymphocytes in LN, enrichment of this population, and analysis of effector cell function will be investigated. Well defined murine tumor models of adoptive immunotherapy will be utilized to test the hypothesis that antigen presenting cells transfer tumor antigens to draining LN. Several adjuvants including GM-CSF will be injected paratumorally to study augmentation of LN T cell sensitization. In the draining LN, antigen primed T cells display altered levels of several membrane markers, among them CD62L (L-selectin), that will be used to enrich tumor-sensitized cells from irrelevant T cells. The production of cytokines upon contact with tumor cells and therapeutic efficacy will be analyzed in the segregated T cell subsets. To mediate tumor regression T cells must contact tumor and transferred cells infiltrate tumors even in immune privileged sites such as the central nervous system. The homing of transferred T cells to tumor and effector mechanisms will be analyzed in mice bearing intracranial tumors. The cell adhesion molecules that mediate adherence of T cells to the tumor vasculature will be defined by their expression in situ, on T cells isolated from tumors, and by interference with tumor infiltration by blocking mAb. T cell mediated tumor regression is highly specific and the contribution of selective trafficking or retention of tumor-reactive cells to this specificity will be determined. Although ex vivo activated T cells are not cytolytic in the standard 51Cr release assay, they do produce cytokines upon contact with tumor. The production of cytokines in vivo, and the participation of accessory cells in mediation of tumor regression will be investigated.