The generation and metabolism of leukotrienes in the ionophore-stimulated blood of normal and asthmatic subjects

Abstract The generation and metabolism of leukotrienes (LTs) 1341 C 4 , D4, and E 4 were studied in vitro in the A23187-stimulated whole blood of normal (N) and atopic asthmatic (AA) human subjects. Using a combination of reversed-phase high performance liquid chromatography and radioimmunoassay, we have demonstrated that the blood cells of atopic asthmatic patients have an enhanced ability to release LTB4 and LTC4 when compared to those of normal subjects. The release of LTB 4 and LTC 4 in response to ionophore is dose- and time-dependent. Half-maximal doses of ionophore caused the generation of high, sustained levels of LTB 4 , which are significantly higher in the AA blood than in N blood. Incubations of 3 H-LTB 4 in ionophore-stimulated N and AA blood revealed a slow metabolism to 20-OH-LTB 4 and 20-COON-LTB 4 . LTC 4 is generated in smaller amounts than LTB4, with an early peak after 10 min which is significantly higher (p 4 elicits significantly greater amounts of LTD 4 , and consistently higher levels of LTE 4 , in the AA blood. Parallel incubations of 3H-LTC 4 in ionophore-stimulated N and AA blood demonstrated rapid metabolism of LTC4 by the glutathione detoxification pathway. The elevated production of LTB 4 and LTC 4 in AA blood was not accounted for by differences in leukocyte sub-type counts in the two groups, nor by differences in their rates of catabolism. The novel, selective 5-lipoxygenase inhibitor BW A4C [N-(3-phenoxycinnamyl) acetohydroxamic acid] caused dose-dependent inhibition of LTB 4 and LTC 4 generation and was equipotent in N and AA blood.