Protective Cytotoxic T Lymphocytes Are Induced During Murine Infection with Chlamydia trachomatis'

T cell responses are often an important component in immunity to organisms that replicate intracellularly. Cyto-toxic T lymphocyte (CTL) recognition of peptide Ag in the context of MHC class I molecules results in lysis of infected cells and the release of cytokines including IFN-y. Members of the genus Chlamydia are obligate intra-cellular pathogens that cause blindness and sexually transmitted disease worldwide. Even though it replicates within a membrane-bound vacuole, Chlamydia trachomatis may elicit a CTL response if Chlamydia Ags are present in the cytoplasmic compartment where they can be processed for presentation and bound by MHC class I. In this study, we characterized a CTL line derived from mice infected with C. trachomatis. This CTL line is specific for, and able to lyse, Chlamydia-infected cells. The peptide epitope recognized by this CTL line is present on infected cells, and is presented to the CTL by the classical MHC class I molecule H-2 Ld. Adoptive transfer of this CTL line into an infected mouse affords protection, and this protection requires the activity of IFN-y. The Journal of Immunology, 1994, 153: 51 83. C hlamydia trachomatis is the most common cause of sexually transmitted disease in the United States and a major cause of preventable blindness world-wide. The diseases caused by C. trachomatis range from sal-pingitis and conjunctivitis to the systemic infection lympho-granuloma venereum. All known Chlamydia species ar