Effect of interferon-γ, in vitro and in vivo, on mRNA levels of phagocyte oxidase components

During the international placebo-controlled trial on the efficacy of interferon-γ (IFN-γ) in chronic granulomatous disease (CGD), 19 patients entered the study via our Institute. One patient stopped treatment shortly thereafter. RNA was purified from the mononuclear cells of the remaining 18 CGD patients before and during this placebo-controlled trial. The mRNA levels for the NADPH oxidase components were subsequently analyzed. Compared with the placebo-treated CGD patients, the mRNA levels for p47-phox were significantly increased in the IFN-γ-treated CGD patients (P < 0.002). No significant changes were observed in the mRNA levels of the other oxidase components. These findings are in agreement with observations in vitro and indicate that IFN-γ is active on the NADPH oxidase in vivo as well. However, it remains questionable whether these effects in vivo can explain the observed reduction of infections in these patients.