Whole-cell pertussis found in diphtheria-tetanus-pertussis (DTP) vaccine can produce symptoms reminiscent of biological responses to circulating proinflammatory monokines such as IL-6, IL-1beta, and TNFalpha. Therefore the ability of pertussis-containing vaccines and several heat-killed Bordetella pertussis preparations to stimulate cytokine production in a human monocytic cell line, THP-1, were examined. The whole-cell pertussis vaccine induced significantly more IL-6, IL-1beta, and TNFalpha production than did the acellular pertussis or diphtheria-tetanus-only vaccine. Polymyxin B was able to inhibit most of the IL-6 induced by pertussis endotoxin and a heat-killed preparation of B. pertussis containing a null mutation in bvgAS, a regulatory locus required for expression of all known protein virulence factors synthesized by this organism. However, it only partially inhibited IL-6 production induced by other pertussis-containing preparations, including DTP vaccine. These results indicate that in vitro whole-cell vaccine is a potent stimulator of IL-6, IL-1beta, and TNFalpha. They also suggest that although endotoxin is a major inducer of IL-6, other components of B. pertussis also contribute to IL-6 production by monocytes.