Overall objective of this proposal is to isolate and identify peptides corresponding to variable regions of an immunoglobulin (antibody molecule) of a B-cell lymphoma that induce anti-tumor cytotoxic T lymphocytes (CTL) response in context of MHC class 1-gene products. Such variable regions (Id or idiotype) are often unique markers of a B-cell clone and can act as a tumor-associated antigen (TAA) in transformed cells. A B-cell tumor, 2C3, that express both membrane and secreted forms of a clonotypic idiotype (Id/TAA) will be used in this study. It has been shown that prolonged immunization with irradiated 2C3 cells induces CD8+CD4 CTL, and provides lasting protection against regrowth of 2C3 tumor. Similar immunization with the purified Id+ Ig secreted by 2C3 tumor is ineffective, and results in slowly progressing dormant tumors. Results from PI's laboratory revealed that the 2C3 cells express, in addition to bona fide surface Ig, MHC class 1 protein bound """"""""processed"""""""" forms of 2C3 idiotype. Since Id/TAA-specific CTL is pivotal in anti-tumor immunity, an effective prophylactic measure would be one that augments such immunity. This requires understanding of the molecular nature of the epitopes involved in CTL induction in the 2C3 tumor used as a model here. To facilitate this study, the PI has developed (1) specific methodologies, (2) Id-specific CTL lines and clones, and (3) polyclonal and syngeneic monoclonal anti-Id reagents. In addition, they now have the nucleotide sequences of both heavy and light chains of 2C3 Ig. The investigator will address: (1) identify class I major histocompatibility complex (MHC)-restricted idiopeptides involved in the induction of anti-tumor CTL, (2) determine if the epitopes on 2C3 idiotype are primarily derived from the heavy, or the light chains, (3) determine if idiotypes associate with K, D or L molecules of murine MHC complex, and (4) determine if isolated peptides are able to induce anti-tumor CTL. The investigators expect that these studies will lead to an understanding of molecular features of immunoglobulin idiotype that can be successfully exploited to design CTL-inducing anti-tumor response.
