Type-Specific Antibodies in Human Chlamydia Trachomatis Infections of the Eye

Abstract

Sera from humans with ocular chlamydial infections were examined for type-specific antibodies by immunofluorescence before and after extensive cross-absorption with type-specific antigens of Chlamydia trachomatis. In trachoma-inclusion conjunctivitis infections ascribable to types C, A, or F, and occasionally types B and E, the antibody response was so narrow and specific as to make serologic diagnosis of the infecting agent feasible. In other ocular or oculongenital infections with types B, B_a, E, and D, and with lymphogranuloma venereum, there was only a broad antibody pattern. In experimental infections with types F or D, the initial antibody response of volunteers was narrowly directed at the dominant type-specific antigen of the infecting strain; then it broadened with time to include cross-reactive antibodies. In sequential infections with different types, the antibody to the first infecting type was recalled to a higher level by the second, heterotypic infection. In some individuals, treatment with tetracycline drugs resulted both in regression of clinical activity and decrease in antibody titer. Perhaps such a serologic response may indicate loss of antigen and cure.