Identification of Chlamydia trachomatis antigens recognized by human CD4(+) T lymphocytes by screening an expression library

Identification of the immunogenic proteins that induce Chlamydia trachomati s (CT)-specific T cell responses is crucial to the development of protectiv e vaccines and understanding the mechanisms of chlamydia-induced pathology. To characterize the targets of the human T cell response we have used chla mydia-reactive human T cell clones as cellular probes to screen a CT genomi c library expressed in Escherichia coli using peripheral blood mononuclear cells to present antigens. The library was screened with three chlamydia-re active T cell clones of unknown specificity and three novel stimulatory chl amydia antigens were identified. These E. coli recombinants were shown to e xpress the chlamydia proteins, enolase, pmpD and CT579. Enolase and pmpD pr oteins were purified and shown to induce the proliferation of synovial flui d mononuclear cells isolated from the knee joints of patients suffering fro m chlamydia-associated reactive arthritis. We suggest that these stimulator y antigens are common targets of the T cell response in this group of patie nts. A greater understanding of T cell-mediated immunity in uncomplicated C T infection, and in patients with CT-induced chronic inflammatory disease ( trachoma, salpingitis, arthritis) may identify the principal immune respons es associated with immunopathology.