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.
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