Role of gamma-delta T cells in murine Chlamydia trachomatis infection.

The role of gamma-delta T cells in host resistance to Chlamydia trachomatis was characterized by using a murine model of pneumonia caused by the mouse pneumonitis agent (MoPn), murine C. trachomatis. At days 3 and 7 after infection, gamma-delta T-cell-deficient knockout mice had significantly higher levels of MoPn in the lungs than did immunologically intact controls. At day 20, paradoxically, gamma-delta T-cell-deficient mice were more resistant to MoPn than were controls. This increased resistance was not due to an increased production of toxic cytokines or interleukin-10 in controls on that day. Gamma-delta T cells play a role in protection early in MoPn infection, but they may be deleterious later in infection, as has been observed in models of salmonella and trypanosome infection.