HEPOXILIN BINDING IN HUMAN NEUTROPHILS

Hepoxilins have previously been shown to release intracellular calcium in human neutrophils. We show herein that tritium-labeled hepoxilin A (3) of high specific radioactivity binds to human neutrophils, and thi s binding is reversed by the addition of unlabeled compound, demonstra ting that specific binding for these compounds exists in these cells. Specific binding of both the methyl ester derivative as well as the fr ee acid form of the hepoxilin takes place in broken membrane fragments . In contrast only the methyl ester derivative binds specifically to t he intact cells. We also show that intact neutrophils form hepoxilin A (3) when incubated in the presence of the hepoxilin precursor, 12(S)-H PETE. These data demonstrate that hepoxilin synthesis can occur in the neutrophil and that hepoxilin binding sites, which appear to be locat ed intracellularly, exist in these cells. (C) 1995 Academic Press, Inc .