Serological observations of Pneumocystis carinii infection in humans

Serological examinations of Pneumocystis carinii antigen and antibody were performed in adult patients with P. carinii pneumonia. The antibody titer was assayed by indirect immunofluorescence, and antigenemia was detected by counterimmunoelectrophoresis. Profiles of the time course of antibody levels in serum indicated that development of the antibody occurred at an early stage of pneumonia and that peak titers were obtained during the febrile stage.