The effects of interferon- α on oxygen radical production by human neutrophils

This study was done to determine if the production and metabolism of reactive oxygen species from human neutrophils were modulated by the treatment of interferon- α (IFN- α). Luminol-dependent Chemiluminescence(LmCL) responses were inhibited by a high concentration of IFN- α (more than 1 X 10⁴IU/ml)when opsonized zymosan(OZ) and phorbol 12- myristate 13-acetate(PMA) were used as stimulants. However, these responses were increased by 1 X 10³IU/ml of IFN- α with Ca²⁺-ionophore A23187 stimulation. Lucigenin-dependent Chemiluminescence(LgCL) responses were inhibited by all concentrations. These findings suggest the possibility that IFN- α inhibits activation of protein kinase C(PKC), whereas the resulting effect might be due to the inhibition of myeloperoxidese(MPO) degranulation. Preincubation of human neutrophils with IFN- α for 30,60 or 120 minutes and subsequent stimulation with OZ, PMA and Ca²⁺-ionophore A23187 caused an increase LgCL responses, while inhibiting LmCL responses. These findings suggest that preincubation of human neutrophils with a high concentration of IFN- α might enhance the NADPH-oxidase activity, although a relative increase of LgCL was due to the inhibition MPO degranulation.