[The effects of interferon-alpha 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-alpha (IFN-alpha). Luminol-dependent Chemiluminescence (LmCL) responses were inhibited by a high concentration of IFN-alpha (more than 1 x 10(4) IU/ml) when opsonized zymosan (OZ) and phorbol 12-myristate 13-acetate (PMA) were used as stimulants. However, these responses were increased by 1 x 10(3) IU/ml of IFN-alpha with Ca(2+)-ionophore A23187 stimulation. Lucigenin-dependent Chemiluminescence (LgCL) responses were inhibited by all concentrations. These findings suggest the possibility that IFN-alpha 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-alpha for 30, 60 or 120 minutes and subsequent stimulation with OZ, PMA and Ca(2+)-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-alpha might enhance the NADPH-oxidase activity, although a relative increase of LgCL was due to the inhibition MPO degranulation.