Antigenic specificity of serological response in Chlamydia trachomatis urethritis detected by immunoblotting.

Sera from 19 patients with Chlamydia trachomatis culture positive non-gonococcal urethritis were studied for the presence of antibodies to chlamydial proteins by immunoblotting. Ten C trachomatis negative patients with non-gonococcal urethritis and 10 healthy controls were also studied. Acute phase sera from C trachomatis positive patients with non-gonococcal urethritis reacted only with the major outer membrane protein whereas all the convalescent phase serum samples reacted with the major outer membrane protein and with a 60,000 and a 62,000 molecular weight protein. Some sera also reacted with a 45,000 molecular weight protein. Five of 10 convalescent phase samples from patients with C trachomatis negative non-gonococcal urethritis showed a reaction pattern comparable with that observed in convalescent sera from C trachomatis from C trachomatis positive patients with non-gonococcal urethritis. Sera from healthy seronegative subjects were negative by blotting.