Stimulation of neutrophil oxygen-dependent metabolism by human leukocytic pyrogen.

The ability of highly purified human leukocytic pyrogen (LP) to stimulate neutrophil oxygen-dependent metabolism was studied. Human peripheral blood neutrophils exposed to leukocytic pyrogen in vitro demonstrated an increase in the percentage of neutrophils reducing nitroblue tetrazolium (NBT) dye and a marked stimulation of superoxide dismutase inhibitable reduction of ferricytochrome c. LP stimulation of neutrophil oxygen-dependent metabolism was dose and time dependent. Procedures that destroyed the pyrogenicity of LP also abolished the effects on neutrophil metabolism. Neutrophil hexose monophosphate shunt activity was also stimulated by LP. In a rabbit model, the effect of in vivo LP on neutrophil superoxide generation was also studied. There was a consistent increase in the percent and absolute number of NBT positive neutrophils. Peak stimulation of neutrophil metabolism occurred after defervescence suggesting several possible mechanisms. The observations reported here may, in part, explain the nonspecificity of the NBT test in febrile, noninfected patients and provide further understanding of neutrophil physiology during acute inflammation.