Increased nitroblue tetrazolium dye reduction by human neutrophils stimulated by interferon in vitro.

Human leukocyte interferon enhanced nitroblue tetrazolium dye (NBT) reduction by human neutrophils (PMNs). Increase in NBT reduction paralleled increase in interferon dose. When human leukocyte interferon was heated to 60 C or 80 C for 30 min, both the antiviral activity and the effect on NBT reduction decreased. Human leukocyte interferon neutralized with anti-human leukocyte interferon serum showed no effect on NBT reduction. A human fibroblast interferon preparation also enhanced NBT reduction. The species dependency of interferon was shown in NBT reduction as well as in antiviral activity.