Generation of leukotriene B4 by human lung fragments and purified human lung mast cells.

Leukotriene B4 (LTB4) is a potent stimulus for neutrophil chemotaxis, aggregation, and activation. Although this mediator has been postulated as a possible stimulus for the neutrophil accumulation seen after mast cell triggering in vivo, the ability of human mast cells to produce this leukotriene has never been described. The purpose of this study was to investigate the ability of purified human lung mast cells and mast cells in lung fragments to generate leukotriene B4 after immunologic (anti-IgE) and nonimmunologic (calcium ionophore, A23187) activation. Release of LTB4 was quantitated by 2 specific radioimmunoassays with biochemical characterization by high performance liquid chromatography. In a first series of experiments using radioimmunoassay 1, purified human lung mast cells (n = 10) released LTB4 in response to both an immunologic and nonimmunologic stimulus in a time- and dose-dependent manner. In response to an optimum concentration of anti-IgE (3 micrograms/ml), mast cells of 4.5 to 98% purity, generated 6.2 +/- 1.7 ng immunoreactive LTB4 (iLTB4)/10(6) mast cells. HPLC characterization revealed that 30 +/- 0.3% of the iLTB4 coeluted with standard synthetic LTB4 in these studies. In a second series of experiments using radioimmunoassay 2, mast cell activation resulted in the release of 0.5 to 1 ng iLTB4/10(6) mast cells with greater than 75% coeluting with synthetic LTB4. Thus, we estimate that human lung mast cells can generate approximately 1 to 2 ng of LTB4 per million mast cells.(ABSTRACT TRUNCATED AT 250 WORDS)