Human alloreactive CTL clones: loss and reacquisition of specific cytolytic activity can be regulated by "recombinant" interleukin 2.

In this communication, we demonstrate that human alloreactive CTL at the clonal level, can undergo reversible processes vis-a-vis lytic function: from a highly lytic phase to a nonlytic quiescent phase and back to a lytic phase. "Reversion" and reacquisition of function can be controlled by removing or adding back a chromatographically purified product of a human interleukin 2 gene (rIL 2) that appears to serve, either directly or indirectly, as a lysis-inducing signal for these CTL.