A PEPTIDE OF CHLAMYDIA-TRACHOMATIS SHOWN TO BE A PRIMARY T-CELL EPITOPE IN-VITRO INDUCES CELL-MEDIATED-IMMUNITY IN-VIVO

Chlamydiae are a major cause of infertility and preventable blindness and there is currently no effective vaccine in humans or rodents again st these organisms. We have previously shown that a peptide of 12 amin o acids (termed TINKP) from a conserved region of the major outer memb rane protein (MOMP) of Chlamydia trachomatis (C. trachomatis) is a pri mary T-cell epitope in humans. Here we showed that when dendritic cell s (DC) from C3H or BALB/c mice were pulsed in vitro with the peptide t hey stimulated proliferation of syngeneic T cells in vitro indicating that the peptide is also a primary T-cell epitope in mice. Since the s kin is a rich source of DC, we immunized mice from each strain with an intradermal injection of the peptide. Humoral and cell-mediated immun ity to peptide, MOMP or whole elementary bodies (EB) of C. trachomatis (F/NI1/GU) were assessed. No antibody response to TINKP was observed. However, immunized mice showed recall responses to all three chlamydi al antigens. T-cell-mediated immunity in the absence of antibody was i nduced by a single injection of the peptide intradermally. C. trachoma tis isolated from the human genital tract causes salpingitis in mice. Preliminary studies in susceptible C3H mice indicated that intradermal injection of peptide conferred some protection against the developmen t of salpingitis. Thus, a primary T-cell epitope identified by in vitr o stimulation using DC can also initiate cell-mediated immunity in viv o and this approach may be useful in the development of vaccines.