We have reported that secretory phospholipase A2 (sPLA2) enzymes are elevated in the BAL fluid of asthmatic patients following inhaled allergen challenges, but the sources and functional impact of the sPLA2 enzymes are unknown. Eosinophils infiltrate lung mucosa during allergic asthma episodes, and eosinophils secrete inflammatory proteins, including sPLA2. We and others have found that eosinophils contain 14-fold to 50-fold more sPLA2 protein than neutrophils. We found that eosinophils secrete sPLA2in vitro rapidly (peak in 2 min), while neutrophil secretion of similar enzymatic activity is continuous for > 15 min. We have now specifically identified the group IID messenger RNA, isolated from peripheral blood eosinophils using reverse-transcriptase polymerase chain reaction.