Epidemiological and genetic correlates of incident Chlamydia trachomatis infection in North American adolescents.

Epidemiological and genetic correlates of Chlamydia trachomatis infection were examined prospectively in 124 male and 361 female adolescents at high risk for human immunodeficiency virus type 1 (HIV-1) infection. Seventy percent of subjects were African American, and 68% had HIV-1 infection. As expected, younger age (<17 years), multiple sex partners (> or =2), and prior chlamydial infection predicted chlamydial infection during a 6-56-month follow-up period (P=.02, P=.02, and P=.03, respectively). Human leukocyte antigen (HLA) class II variant DQB1*06 (mostly *0602 and *0603) was associated with chlamydial infection (49% vs. 34%; adjusted relative odds [RO], 1.8; P=.005), as was HLA class I haplotype B*44-Cw*04 (10% vs. 4%; RO, 3.2; P=.009). DQB1*06 was found in 9 (75%) of 12 female adolescents with chlamydial pelvic inflammatory disease. In contrast, sex, ethnicity, and HIV-1 infection did not predict chlamydial infection. These findings suggest that antigen presentation in adaptive immune responses may serve as a major factor in effective control of C. trachomatis infection. The underlying mechanisms remain to be experimentally elucidated.