The goal of this project is to explore and understand immunological mechanisms that may be important in initiation or control of disease processes. We transformed by SV40 virus a cell type in the thymus which had many features of thymic epithelial cells, including morphology, both light and EM, and the presence of keratin. The cell surface had MHC antigens of Class I type. Supernatants of these cells were capable of inducing cytotoxic effector cell capacity in thymocytes. These cell lines may be important for delineating cell interactions that lead to T cell differentiation in the thymus. We are also investigating biochemical properties of tumor-associated transplantation antigen TSTA of guinea pig B cell L2C leukemia of inbred Strain 2 guinea pigs, whose is resistant to boiling. It may represent a new class of antigens on normal B cells and once identification is completed, a similar class of materials could be looked for on human B cell malignancies. We are studying binding of P.falciparum infected erythrocytes to umbilical vein endothelial cells in culture, reproducing a process that occurs in vivo. We discovered that a human melanoma cell line also binds and will greatly expedite isolation of this receptor for malaria-infected red cells.