The ability of interleukin 2 (IL-2) to stimulate p72 syk activity in intact porcine peripheral blood lymphocytes was examined. We demonstrated that IL-2 activated p72 syk in a time- and dose-dependent number, for which its peak time and maximum responsive dose were 5 min and 100 U/ml, respectively. This activation was observed only in cytosolic fractions and not in membrane ones. However, IL-2 failed to induced calcium mobilization. Moreover, IL-2-inducible p72 syk activation was not affected when extra and intracellular calcium was depleted. These data suggest that the IL-2 signaling pathways through p72 syk in peripheral blood lymphocytes is different, at least in part, from other agonist, such as concanavalin A in polymorphonuclear neutrophils which can trigger both the activation of p72 syk and intracellular calcium mobilization.
