An animal model of Pneumocystis carinii pneumonia and therapeutic efficacy of interferon-gamma in this model

To evaluate the efficacy of drugs for treatment, we tried to make an animal model of Pneumocystis carinii (P. carinii) pneumonia. Specific pathogen free (SPF) rats immunosuppressed with corticosteroid were intratracheally inoculated with P. carinii. Six weeks after the inoculation, the lung sections of infected rat lung showed increased numbers of P. carinii in the alveoli and thickening of alveolar septa with mononuclear cell infiltration. From 7 to 9 weeks after inoculation, the intensity of infection became more severe, and some rats died at this period. Then, to evaluate drug efficacy in this model, we finished the drug therapy by the 6th week and used the number of P. carinii in the lung and the inflammation score as an indicator of drug efficacy. In this P. carinii pneumonia animal model, both sulfamethoxazole-trimethoprim clinically established anti P. carinii drug and interferon-gamma which is one of the lymphokines mainly produced by T lymphocytes indicated therapeutic and synergistic efficacy against P. carinii pneumonia.