PRODUCTION OF 15-HYDROXYEICOSATETRAENOIC ACID BY PURIFIED HUMAN EOSINOPHILS AND NEUTROPHILS

In the presence of high concentrations of exogenous arachidonic acid (≥ 10 μm). eosinophils produced 15‐hydroxycicosatetraenoic acid (15‐HETE) in the absence of stimuli. The calcium ionophore A23187, as well as the chemotaxins used in this study‐complement split product C5a, platelet‐activating factor (PAF). and,N‐formyl‐methionyl‐leucyl‐phenylalanine(FMLP)–failed to increase 15‐HETE production, indicating that eosinophil 15‐lipoxygenase is already active Production of 15‐HETE from eosinophils increased with increasing concentrations of arachidonic acid, exogenously added. Maximal 15‐HETE production was observed to he 1111 ± 380 ng per 106 eosinophils at the concentration of 100μm of arachidonic acid. With low concentrations of exogenous arachidonic acid (below 2;μm). eosinophils were considered to incorporate exogenous arachidonic acid into their cell membrane, and did not produce 15‐HETE. In contrast, 15‐HETE formation in highly purified neutrophils (eosinophils < 1%) was negligible compared with that in eosinophils (.300‐fold less), suggesting that 15 f HETE‐forming activity in granulocytes is derived from the eosinophil 15‐lipoxygetiase pathway and that neutrophils may lack 15‐lipoxygcnase activity. Copyright © 1990, Wiley Blackwell. All rights reserved