The palatine tonsil is the most important element of Waldeyer's ring as a defense mechanism against various microorganisms. The neutrophils are the initial active participants in bacterial infection and inflammation, but their interaction with other cellular participants is poorly understood. To clarify this point, the effects of culture supernatant from human tonsillar cells on the peripheral neutrophil function were investigated. Supernatants from tonsillar cells were incubated in the presence or absence of streptococcal preparation (OK-432) enhanced chemiluminescence, adherence, phagocytosis, chemotaxis, and superoxide production of human peripheral neutrophils. The results suggest that tonsils play an important role in the regulation of neutrophil function.