AGONIST-INDUCED LIPOXIN A(4) GENERATION - DETECTION BY A NOVEL LIPOXIN A(4)-ELISA

Lipoxin A(4) (LXA(4)) possesses potent bioactions. To facilitate its d etection, an enzyme linked immunosorbent assay (ELISA) was developed t hat proved sensitive and selective. Quantitation by ELISA of LXA, gene rated from cellular sources strongly correlated (r = 0.99) with values obtained by high-pressure liquid chromatography (HPLC). We used this LXA(4)-ELISA to examine parameters influencing LXA(4) generation from endogenous substrates during human platelet neutrophil (PLT-PMN) inter actions in vitro. Agonist induced LXA(4) production was clearly eviden t at a PLT-PMN ratio of 10:1, and recombinant human granulocyte/monocy te colony stimulating factor-priming of PMN augmented LXA(4) generatio n 5-6 fold. The chemotactic peptide formylmethionyl-leucyl-phenylalani ne, platelet-derived growth factor and arachidonic acid (20:4n-6) each stimulated formation of immunoreactive LXA(4) (iLXA(4)) in these co-i ncubations. The presence of iLXA(4) was also evaluated in vivo in aspi rin-sensitive asthmatic patients who, in a randomized, double-blind cr ossover design, underwent nasal lavage after they each ingested a pred etermined threshold dose of aspirin or placebo. Aspirin challenge prov oked statistically significant increases in iLXA(4) in each patient (P < 0.005). These results validate the use of a solid-phase ELISA for d etection of LXA(4). Furthermore, the use of this ELISA has allowed the first documentation of iLXA(4) formation in human subjects with aspir in-sensitive asthma following specific antigenic challenge.