Despite an increasing understanding of the pathophysiologic mechanisms underlying immunologic diseases, antigen- specific therapies are lacking. Development of antigen-specific therapies is critical because nonspecific therapies are often unable to induce durable remissions and are limited by significant toxicities. This proposal describes the development of a novel antigen-specific immunotherapy for autoimmune and alloimmune diseases. Genetically modified T cells (GM-TCs) were created that are able to specifically recognize and destroy or divert pathologic T cells. The GM-TCs do this with surrogate T cell receptors that, in a single chain, link T cell receptor (TCR) signaling domains, MHC molecules, and antigenic peptides. The TCR of pathologic T cells is complementary to and recognizes the MHC-antigen domain of the chimeric receptor. This recognition activates the GM-TC through the chimeric receptor's signaling domain. The GM-TCs can proliferate, secrete cytokines, and kill the pathologic T cells. In initial studies, adoptive transfer of GM-TCs into susceptible mice suppressed autoimmune disease. Several aims are proposed to further explore how GM-TCs affect the T-cell repertoire in mouse model systems and how GM-TCs may best be applied to treat autoimmune and alloimmune conditions. Signal transduction through the chimeric receptors will be studied. The effect of integrating signaling domains from costimulatory and co-receptor molecules into chimeric receptors will be analyzed to determine whether these domains can enhance signaling (Specific Aim 1). In vitro functional assays will be used to determine the therapeutic potential of GM-TCs expressing different chimeric receptors. Quantitative assays of T cell function and number will be performed to determine the in vivo impact of GM-TCs on the immune repertoire (Specific Aim 2). The effectiveness GM-TCs in treating an experimental CD4+ T cell mediated autoimmune disease (experimental autoimmune encephalomyelitis) and a CD8+ T cell-mediated alloimmune condition (skin graft rejection) will be studied (Specific Aim 3). It is hypothesized that immunoregulatory GM-TCs will downmodulate autoimmunity or alloimmunity by disrupting pathological effector mechanisms and that cytolytic GM-TCs will kill alloimmune or autoimmune effecter T cells. The cell dynamics and homing properties of GM-TCs will be analyzed to clarify the in vivo cellular properties that influence therapeutic efficacy (Specific Aim 4). Together this information will provide a starting point for the application of GM-TCs to human immunologic conditions.
