REDUCTION OF NITROBLUE TETRAZOLIUM FOR FUNCTIONAL-EVALUATION OF ACTIVATED MACROPHAGES IN THE CELL-MEDIATED IMMUNE-REACTION

In phagocytic cells nitroblue tetrazolium (NBT) is reduced to formazan. This, in turn, is deposited as a dark blue precipitate in the cytoplasm. Stimulation of the hexosemonophosphate (HMP) shunt leads to increased reduction of NBT. Changes in reduction capacity can be quantitated by the extraction and photometrical evaluation of formazan. Data presented here demonstrate that quantitative evaluation of intracellular formazan is a sensitive indicator for mediators of cellular immunity (MCI) activating marcophages. The NBT reduction potential was increased by a factor of 3.7 if bovine γ globulin (BGG) immune peritoneal exudate (PE) cells were incubated with BGG or if MCI-rich culture supernatants were transferred to normal PE cells. The increased NBT reduction was always paralleled by increased inhibition of capillary migration and by positive skin testing. These experiments suggest that the test for NBT reduction may be a quantitative evaluation of MCI activity. © 1979.