We are studying the interactions between lymphoid cells and potentially oncogenic viruses in mouse and man. Immunological activation of both oncornaviruses and cytomegaloviruses has been described in mice. Attempts will be made to activate similar agents from human lymphoid cells in vitro. Reactivity to endogenous oncornaviruses has also been demonstrated in mice. We will attempt to demonstrate similar reactivity against primate oncornaviruses in man. Cell-mediated autoimmunity is a feature of carrier states in mice infected with leukemia viruses. We will attempt to elucidate the mechanisms underlying such autoimmunity. BIBLIOGRAPHIC REFERENCES: Phillips, S.M., Gleichmann, H., Hirsch, M.S., Black, P.H., Merrill, Jr., Schwartz, R.S. and Carpenter, C.B. Cellular immunity in the mouse. IV: Altered thymic dependent lymphocyte reactivity in the chronic graft vs host reaction. Cell Immunol. 15:152-168, 1975. Phillips, S.M., Hirsch, M.S., Andre-Schwartz, J., Solnik, C., Black, P.H., Schwartz, R.S., Merrill, J. and Carpenter, C.B. Cellular immunity in the mouse. V: Further studies on leukemia virus activation in allogenic reactions of mice: stimulatory parameters. Cell Immunol., 15:169-179, 1975.