This study was performed to observe the therapeutic effects of interferon-gamma(IFN-gamma) and gamma-globulin(gamma-globulin) in experimental Pneumocystis carinii pneumonia of immune suppressed mice. After 9 weeks, trimethoprim-sulfamethoxazole(TMP-SMZ; 10-50 mg/mouse/day), mouse IFN-gamma(5 x 10(4) units/mouse/day) and mouse gamma-globulin(20 mg/mouse/day) were administered to the mice for 3 weeks by the experimental group. The therapeutic efficacy was evaluated by body weights, histopathologic and electron microscopic findings of the lungs, and number of P. carinii cysts by Gomori's methenamine silver stain. Body weights of the mice were significantly increased in the group of combination therapy of TMP-SMZ with IFN-gamma or gamma-globulin, and in the group of TMP-SMZ treatment (p < 0.05), however, little effect was found in the group of gamma-globulin alone. Histopathologic findings of P. carinii pneumonia were much improved in the group of combination therapy of TMP-SMZ with IFN-gamma. Treatment with either TMP-SMZ or IFN-gamma significantly reduced the number of cysts in the P. carinii pneumonia, but gamma-globulin alone was ineffective. In electron microscopic findings of P. carinii pneumonia, the number of trophozoites and cysts were reduced by treatment with either TMP-SMZ or IFN-gamma, and most of the cysts were empty or containing one or two intracystic bodies. The present results suggested, that combination therapy of TMP-SMZ with IFN-gamma had synergistic effects in treatment of P. carinii pneumonia in experimental mice.
