IMMORTALIZATION OF HUMAN T-CELL CLONES BY HERPESVIRUS-SAIMIRI - SIGNAL-TRANSDUCTION ANALYSIS REVEALS FUNCTIONAL CD3, CD4, AND IL-2 RECEPTORS

Investigation of human activated T cells has been complicated by the n eed for periodic restimulation with Ag/mitogen and accessory cells and by the limited life span of most human T cell clones. To overcome the se problems, we have transformed established human T cell clones to pe rmanent growth with Herpesvirus saimiri, a lymphoma-inducing virus of nonhuman primates. Three human CD4+ T cell clones were investigated in detail. They have been growing in the presence of exogenous IL-2 but without restimulation with mitogen or feeder cells for more than 11 mo with doubling times between 2 and 4 days. In contrast, their nontrans formed parent clones needed to be restimulated with PHA and feeder cel ls every 14 to 21 days. To compare responses of H. saimiri-transformed clones with those of their parent clones, we stimulated the cells wit h IL-2 or with anti-CD3 and/or anti-CD4 mAb with and without cross-lin king on the cell surface. Transformed and nontransformed T cell clones were strikingly similar in parameters of early signal transduction, n amely, tyrosine phosphorylation and mobilization of calcium. Ligation of their TcR/CD3 complexes by mAb or by Ag in the presence of autologo us accessory cells increased the proliferation and the secretion of IF N-gamma. Taken together, we have shown that human T cell clones immort alized with H. saimiri express functional CD3, CD4, and IL-2R. They co nstitute a simple, stable, reproducible and accessory cell-free model system for the investigation of signal transduction events in activate d human T cells.