Hepoxilin binding in human neutrophils.

Hepoxilins have previously been shown to release intracellular calcium in human neutrophils. We show herein that tritium-labeled hepoxilin A3 of high specific radioactivity binds to human neutrophils, and this binding is reversed by the addition of unlabeled compound, demonstrating that specific binding for these compounds exists in these cells. Specific binding of both the methyl ester derivative as well as the free acid form of the hepoxilin takes place in broken membrane fragments. In contrast only the methyl ester derivative binds specifically to the intact cells. We also show that intact neutrophils form hepoxilin A3 when incubated in the presence of the hepoxilin precursor, 12(S)-HPETE. These data demonstrate that hepoxilin synthesis can occur in the neutrophil and that hepoxilin binding sites, which appear to be located intracellularly, exist in these cells.