INHIBITORS IN URINE OF RADIOIMMUNOASSAY FOR THE DETECTION OF GONOCOCCAL ANTIGENS

Several substances in urine were found to inhibit the radioimmunoassay of added gonococcal antigens. The supernatants of two-thirds of urine samples from male patients with either gonorrhoea or non-specific urethritis (NSU) were inhibitory. The inhibition caused by many, but not all, samples was reduced or completely abolished by the addition of soybean trypsin inhibitor (STI); STI-sensitive inhibition is thought to be due to proteolytic enzymes, probably from pus cells. Their inhibitory effect was shown to be due to their action on gonococcal antigens and not on antibodies in the assay system. Some supernatants contained other inhibitors unaffected by STI; some of these were dialysable and others were not. Sediments from the urine of patients with NSU or gonorrhoea were often strongly inhibitory, but treatment with STI anulled all but very slight inhibition. STI-treated sediments could, therefore, be used in an assay designed to detect gonococcal antigens.