Transformation of owl monkey T cells in vitro with Herpesvirus saimiri.

Owl monkey peripheral blood mononuclear cells were treated with phytohemagglutinin and expanded in interleukin 2 (IL-2)-containing medium. The cells were then exposed to Herpesvirus saimiri (HVS strain S295C)-infected owl monkey kidney monolayer cells. Four to 6 weeks later, the lymphocytes showed increased clumping and cell growth and the ability to grow in the absence of IL-2. Control lymphocyte cultures not exposed to HVS eventually died out at approximately 6-8 weeks, even in the presence of IL-2. Although infected lymphocytes grew continuously in the absence of IL-2, their growth was enhanced by addition of IL-2 to the cultures. Natural killer cell-like cytotoxicity and gamma-interferon release were also enhanced by IL-2. All cultures were positive for HVS antigens, infectious centers, or DNA. The reactivity of monoclonal antibodies to cell surface markers suggested that the resultant cell lines were comprised of activated T cells. The properties of the in vitro-transformed cells were similar to those of cells established from HVS-induced owl monkey tumors. Our results suggest that infection of T lymphocytes with HVS results in decreased dependence of T cells upon exogenous IL-2 for growth.