Cellular immune response during uncomplicated genital infection with Chlamydia trachomatis in humans.

A lymphocyte transformation (LT) assay for the study of the cellular immune response to Chlamydia trachomatis in humans is described. Subjects studied included 9 newborns whose mothers were C. trachomatis culture negative, 16 seronegative, sexually inexperienced adults, and 107 patients seen at a sexually transmitted disease clinic, including 31 men presenting with acute nongonococcal urethritis and 76 women with known or suspected uncomplicated gonorrhea or with uncomplicated C. trachomatis genital infection. LT stimulation indices (SI) were less than 3.5 in newborns and normal adults, as well as 11 of 12 seronegative, isolation-negative sexually transmitted disease clinic subjects. LTSI greater than 3.5 was found only with subjects who were sero- or culture positive for C. trachomatis. Among men with nongonococcal urethritis, the LTSI correlated better with culture than with antibody. Among women, the LTSI correlated better with antibody than with culture. LTSI decline significantly 3 to 4 weeks after curative therapy in men with nongonococcal urethritis, suggesting that LT response is short-lived and that the LTSI may be an indicator of acute C. trachomatis infection. The sensitivity, specificity, and predictive value of a positive LT assay and of serum and local antibody tests, in terms of C. trachomatis infection defined as positive isolation, were also compared. The predictive value of a positive LTSI for C. trachomatis infection was generally low in the sexually transmitted disease clinic patients: 62% in men with nongonococcal urethritis and 37% in women. However, this study did show the LT assay to be a useful specific test for monitoring the cellular immune response to C. trachomatis infection.