Background: We previously demonstrated that apricot sulfurization workers are exposed to high concentrations of SO2, subsequently causing asthma-like syndrome. This study investigated the effects of SO, exposure on serum TNF-alpha, IL-1beta, IL-6, IL-8, nitrite and nitrate levels to understand the mechanism of SO-induced bronchoconstriction in asthma-like syndrome. Methods: We measured the serum levels of the cytokines, direct nitrite, total nitrite and nitrate obtained from 40 volunteer workers after an hour of exposure to SO2 and 23 healthy controls. Results: The concentrations of the cytokines, direct nitrite, total nitrite and nitrate were significantly (p < 0.0001) higher in the workers than in the controls. The mean serum concentrations of TNF-alpha, IL-1beta, IL-6, IL-8, direct nitrite, total nitrite and nitrate were 430.60 +/- 397.03 pg/ml, 436.67 +/- 316.31 pg/ml, 752.11 +/- 394,95 pg/ml, 262.12 +/- 287.99 pg/ml, 7.75 +/- 3.34 mumol/l, 115.72 +/- 48.78 mumol/l and 107.97 +/- 46.19 mumol/l in the workers, while they were 9.83 +/- 3.12 pg/ml, < 5 pg/ml, 7.49 +/- 1.27 pg/ml, 9.38 +/- 1.99 pg/ml, 2.17 +/- 0.77 mumol/l, 59.91 +/- 7.56 mumol/l and 57.74 +/- 7.20 mumol/l in the controls, respectively. Conclusion: These results show that TNF-alpha, IL-1beta, IL-6, IL-8 and nitric oxide may play a role in the pathogenesis of bronchoconstriction in asthma-like syndrome due to the SO2 exposure. (C) 2003 Elsevier B.V. All rights reserved.