1153 PNEUMOCYSTIS CARINII ANTIGEN AND ANTIBODY IN CHILDREN WITH PNEUMONIA

Serologic profiles of Pneumocystis carinii (PC) based upon incidence of antigenemia & IgG antibody (AB) titers in pediatric patients in Papua, New Guinea (NG) & Memphis, TN support the ubiquity of PC. PC IgG AB was titered by an enzyme-linked immunosorbent assay & antigenemia was detected by a counterimmunoelectrophoresis test, both developed in our laboratory. Antigen (AG) used in the ELISA test was derived from cell culture-grown PC. NG children with pneumonia (N=188) had higher anti-PC titers than U.S. controls (N=50). Those with PC AG (+) pneumonia had highest titers (geometric mean titer = 277), suggesting a specific immune response to PC. Those with PC AG (-) pneumonia (GMT=139) had higher titers than matched U.S. controls (GMT=60), perhaps reflecting more environmental exposure or differences due to socio-economic status. The extent to which PC is responsible for morbidity in multiple-agent pneumonias remains to be elucidated. Since PC is treatable, this represents a high priority goal, as the decision to treat might influence survival in critical cases. Mean AB titers were all significantly different (p=