The detrimental effects of environmental pollutants on the health of the individual are generally accepted, although the mechanisms of these effects remain to be incompletely understood. In the present study, we examined the effects of B[a]P, 2-BP, phenol and TCDD on proinflammatory cytokine gene expression in mice spleen cells which were stimulated with anti-CD3. 10(-9)M TCDD increased IFNgamma and TNFalpha gene expression, but suppressed IL-1 gene expression. 10(-6)M phenol inhibited IL-1, IL-6 and TNFalpha gene expression, and 10(-6)M of 2-BP downregulated TNFalpha gene expression. However, 10(-6)M of B[a]P did not influence on IL-1, IL-6, IFNgamma and TNFalpha gene expression. These findings suggest that TCDD may impair the immune functions of mice by enhancing proinflammatory cytokines production, whereas phenol and 2-BP may impair the functions by inhibiting the production of these cytokines.