Detection of circulating antigens of Pneumocystis carinii in human sera by a sandwich enzyme-immunoassay.

A countercurrent immunoelectrophoresis test has been used for detection of circulating antigens of Pneumocystis carinii in humans; however, this study describes another experiment by sandwich enzyme-immunoassay. Antiserum was prepared by immunizing rabbits with P. carinii cysts which had been propagated in athymic nude rats. Profiles of time course in patients with the positive antigenemia show that P. carinii antigens are detectable prior to an onset of acute pneumonia. Since the sandwich enzyme-immunoassay has an ability of comparing serially monitored levels of the antigen in a quantitative value, the method is to be widely used as a clinical laboratory examination.