Fluorescent antibody studies in chlamydial infections

Irradiated McCoy cells infected with genital strains of Chlamydia trachomatis were grown in wells on slides coated with polytetrafluoroethylene. The inclusions produced in this system formed the antigen in an indirect immunofluorescence test, which detected group-specific chlamydial antibodies in sera from patients attending veneral disease clinics. Chlamydial antibodies were found more frequently and in higher titer in sera from women attending veneral disease clinics then in sera from a less promiscuous population attending a Family Planning Association clinic. Paired sera from 13 patients with nongonococcal urethritis from whom chylamydiae had been isolated were tested against the homologous isolates; seroconversion was demonstrated in only one instance, and antibody was present in the first serum specimens of all the other patients. Chlamydia-specific immunoglobulin M was found in four of eight patients with psittacosis and in a proportion of sera from patients attending veneral disease and Family Planning Association clinics. The antigen for this immunofluorescence test can easily be prepared in laboratories with cell culture facilities for the isolation of C. trachomatis, and the test should be useful for laboratories which cannot undertake the micro-immunofluorescence test.