Effects of nitrogen oxides on natural killer cells in glass craftsmen and braziers

Objectives - To assess the effect of exposure to nitrogen oxides on peripheral blood natural killer cells. Methods - Groups of glass craftsmen and braziers exposed to nitrogen oxides and non-exposed controls were studied. Air concentrations of nitrogen oxides were measured. Mononuclear cells isolated from peripheral blood samples were assayed for natural killer cell activity with K562 target cells in a ⁵¹Cr release assay and the percentage of natural killer cells (CD16) was measured by flow cytometry. Results - Braziers were exposed to 1.2 ppm nitrogen dioxide and 8.6 ppm nitric oxide and glass craftsmen to 2.9 ppm nitrogen dioxide and 26.5 ppm nitric oxide. The natural killer cell activity of exposed workers was significantly lower than in non-exposed controls (P < 0.05 ANOVA Scheffe test). The percentage of natural killer cells in glass craftsmen was significantly greater than in controls (P < 0.05 ANOVA Scheffe test). Regression of natural killer cell activity against age, smoking habit, number of years worked and current exposure to nitrogen dioxide and nitric oxide gases was not significant. The percentage of natural killer cells was not significantly correlated with age, smoking habit, or numbers of years worked, but was significantly related to air concentrations of nitrogen dioxide (P < 0.01) and nitric oxide (P < 0.001). Conclusion - Natural killer cell activity and the percentage of natural killer cells in peripheral blood cells were altered in workers exposed to nitrogen oxides.