UPTAKE OF 12-HETE BY HUMAN BRONCHIAL EPITHELIAL-CELLS (HBEC) - EFFECTS ON HBEC CYTOKINE PRODUCTION

12-HETE, the major lipoxygenase end-product of platelets and macrophag es, may be released in contact of bronchial epithelium in inflammatory diseases of the lung. We have studied the outcome of 12-HETE in prese nce of human bronchial epithelial cells (HBEC). When HBEC were incubat ed with [H-3]12-HETE for 30 minutes, 27.5% of total radioactivity was found in HBEC and 72.5% in supernatants. Unesterified 12-HETE accounte d for 22.4% of total radioactivity, 4.5% being recovered in phospholip ids, preferentially in phosphatidylcholine and phosphatidylethanolamin e. No incorporation in neutral lipids was detected. 72.9% of the incub ated radioactivity was recovered in un identified metabolites. As 12-H ETE has been shown to modulate the expression and production of variou s proteins, the consequence of the 12-HETE uptake on the release of GM -CSF and IL8 by HBEC was assessed. HBEC from control subjects were cul tured for 24 hours with 12-HETE (10(-9) to 10(-7) M) in the presence o r absence of TNF alpha. Detectable amounts of both cytokines were rele ased in the supernatant in basal conditions at 24hr, and TNF alpha inc reased significantly the release of GM-CSF. 12-HETE at 10(-7) M weakly but significantly decreased the TNF-induced release of GMCSF from HBE C. Thus the uptake of 12-HETE could affect the epithelial cell functio n in some situations.