INTERLEUKIN-2 MEDIATES P72(SYK) ACTIVATION IN PERIPHERAL-BLOOD LYMPHOCYTES

The ability of interleukin 2 (IL-2) to stimulate p72(syk) activity in intact porcine peripheral blood lymphocytes was examined. We demonstra ted that IL-2 activated p72(syk) in a time- and dose-dependent manner, for which its peak time and maximum responsive dose were 5 min and 10 0 U/ml, respectively. This activation was observed only in cytosolic f ractions and not in membrane ones. However, IL-2 failed to induce calc ium mobilization. Moreover, IL-2-inducible p72(syk) activation was not affected when extra- and intracellular calcium was depleted. These da ta suggest that the IL-2 signaling pathway through p72(syk) in periphe ral blood lymphocytes is different, at least in part, from other agoni sts, such as concanavalin A in polymorphonuclear neutrophils which can trigger both the activation of p72(syk) and intracellular calcium mob ilization.