Different protein kinase C isoenzymes regulate IL-2 receptor expression or IL-2 synthesis in human lymphocytes stimulated via the TCR.

Stimulation of purified human PBL with mAbs raised against the T cell receptor resulted in an immediate and transient activation of protein kinase C-alpha (PKC-alpha) and PKC-theta, peaking at 10 min, whereas PKC-beta, -delta, and -epsilon were translocated with a delay of >90 min and remained activated for up to 2 h. To characterize specific functions of distinct PKC isoenzymes, Abs against different PKC isoenzymes were introduced by means of electropermeabilization. Neutralization of PKC-alpha and -theta resulted in the complete inhibition of IL-2R expression, whereas anti-PKC-beta, -delta, and -epsilon Abs inhibited IL-2 synthesis. Extensive control experiments have shown that neither electropermeabilization nor control Ig influenced PKC activity and cellular functions. Our data thus clearly show that specific PKC isoenzymes regulate different cellular functions in stimulated human lymphocytes.