Mouse strain-dependent chemokine regulation of the genital tract T helper cell type 1 immune response

Vaginal infection with the mouse pneumonitis agent of Chlamydia trachomatis (MoPn) produces shorter courses of infection in C57BL/6 and BALB/c mice th an in C3H/HeN mice, while C57BL/6 mice are more resistant to oviduct pathol ogy. A robust Th1 response is extremely important in host defense against c hlamydia. In this study we examined gamma interferon (IFN-gamma), interleuk in 10 (IL-10), and the T-cell-regulatory chemokines macrophage inflammatory protein-1 alpha (MIP-1 alpha) and monocyte chemoattractant protein-1 (MCP- 1) to determine if differences in these responses were associated with the differential courses of infection seen in these three strains of mice. Incr eased and prolonged IFN-gamma responses and lower IL-10 responses were obse rved in the C57BL/6 strain compared to BALB/c and C3H. Examination of genit al tract chemokines revealed a marked predominance of MIP-1 alpha over MCP- 1 only in the C57 strain. Thus, a pattern of high MIP-1 alpha and low MCP-1 levels during the first week of infection is associated with an increased Th1 response and a shorter, more benign chlamydial infection. Inhibition of the MCP-1 response in C3H mice increased their later T-cell production of IFN-gamma but decreased their early IFN-gamma response and had no effect on the course or outcome of infection. Inhibition of MCP-1 is not beneficial in chlamydial infection because of its pleiotropic effects.