Effect of recombinant interleukin 5 on the generation of cytotoxic T cells (CTL).

The effect of recombinant human interleukin 5 (rhIL5) on the generation of CTL was investigated by using autologous EBV-transformed B cells as the target. Exogenous IL5 augmented the CTL generation, and its effect was most active at the concentration of 10 ng/ml, and when added at the late phase of culture in this system. IL5 augmented specific CTL activity rather than MHC nonrestricted CTL activity as detected with K562 and Daudi when compared to that augmented by IL2. IL5 did not increase the expression of p55 or p75 IL2R nor the responsiveness to IL2. Taken together with the finding that IL5 augmented the CTL activity even in the presence of cyclosporin A, the effect of IL5 on the CTL generation seems not to act through the IL2-IL2R system.