Leukotriene B4 is measurable in serum of smokers and nonsmokers.

Leukotriene B4 (LTB4), an arachidonic acid metabolite released by neutrophils and macrophages, helps regulate host immune response to antigenic stimulation. LTB4 affects the chemokinesis, aggregation, and enzyme release of neutrophils and stimulates activity of cytotoxic T cells, natural killer cells, and suppressor T cells. LTB4 also has a positive affect on the margination of monocytes and macrophages in the lung in response to inflammatory stimuli. Cigarette smoking represents an inflammatory stimulus in the lung and affects (decreases) the in vitro release of LTB4 by alveolar, macrophages in comparison with that by alveolar macrophages of nonsmokers. By utilizing a sensitive and specific radioimmunoassay we have detected LTB4 concentrations in serum from smokers and nonsmokers. Furthermore, our preliminary data show mean LTB4 concentrations in the serum of smokers to be nearly 60-fold greater than those in nonsmokers, 211 (SEM 35) vs 3.6 (SEM 1.5). Because systemic quantities of LTB4 are now measurable, quantification of this immune system regulatory may be useful in evaluating inflammatory disease states.