Enhancement of nitroblue tetrazolium dye reduction by leukocytes exposed to a component of complement in the absence of phagocytosis.

Enhancement of in vitro nitroblue tetrazolium dye reduction by human polymorphonuclear leukocytes may be mediated by a low molecular weight fluid phase component of the complement system. This occurs in the absence of phagocytosis and is associated with an increase in leukocyte hexose monophosphate shunt activity. The stimulatory component may be generated by activating the alternate complement pathway in serum, and shares many of the properties of human C5a. Thus, the enhanced spontaneous reduction of nitroblue tetrazolium by leukocytes from patients with bacterial sepsis may not necessarily be due to the phagocytic activity of these cells, but rather may occur as a consequence of in vivo complement activation by either intact microorganisms or their products.