Figure 1.

IL-5 activated eosinophil cytosolic phospholipase A₂ (cPLA₂) and CoA-independent transacylase (CoA-IT) with different kinetics in vitro. Eosinophils from healthy individuals without asthma were isolated and incubated with IL-5 for the indicated periods in cell culture, harvested, fractionated, and either cPLA₂ or CoA-IT enzymatic activities assayed as described in Materials and Methods. IL-5 (100 ng/ml) significantly increased cPLA₂ activity (squares) within 30 minutes and maintained that activation for at least 20 hours. However, IL-5 failed to activate CoA-IT (circles) within 30 minutes and required at least 72 hours (at 50 ng/ml) to significantly increase CoA-IT activity in cultured eosinophils. *P = 0.05 by paired t test versus unstimulated 0-minute samples.