: Soluble protein of purified Pneumocystis carinii was prepared from experimentally infected rats. SDS-PAGE of the crude antigen resolved about 20 protein bands from 20 to 200 kDa. Out of them, 116 kDa band strongly reacted and 45-55 and 100 kDa bands reacted weakly to the positive reference human serum from U.S.A. Western blot analysis with sera of 130 normal children and 15 newborns in Korea revealed specific IgG antibody reaction to 40-55 and 116 kDa protein bands. Forty percent (40.0%) of the 145 sera were positive with any of the antigenic protein bands of P. carinii. The positive rate was 56% in 50 males and 33.3% in 48 females. The protein bands 40-55 and 116 kDa from rat P. carinii were confirmed to cross-react with human sera in Korea.
