LOCAL TH1-LIKE RESPONSES ARE INDUCED BY INTRAVAGINAL INFECTION OF WITH THE MOUSE PNEUMONITIS BIOVAR OF CHLAMYDIA-TRACHOMATIS

A critical role for cell-mediated immunity (CMI) has been demonstrated for effecting the resolution of genital infections of mice infected i ntravaginally with the mouse pneumonitis biovar of Chlamydia trachomat is (MoPn). However, little is known about expression of CMI in the mur ine genital tract. The mouse MoPn model was used to examine CMI respon ses in the genital tract and associated lymph nodes during the course of infection. MoPn-specific lymphocytes were present in the genital mu cosa, with the maximum level of proliferation in response to MoPn at 3 weeks postinfection. MoPn-stimulated cells secreting gamma interferon were also detected in the cells from the genital mucosa, but few inte rleukin-4 secreting cells were seen at any time postinfection, indicat ing the induction of a Th1-like response in the cells of the genital m ucosa. The iliac node draining the genital tract was the major node st imulated as a result of a genital infection and exhibited a predominan t Th1-like pattern of cytokine secretion as well. Mesenteric lymph nod e cells demonstrated poor proliferative responses to MoPn and few anti gen-stimulated cytokine-secreting cells after the primary infection. H owever, 7 days after a second infection administered 50 days following the primary infection, there was a marked increase in both proliferat ive responses and the frequencies of MoPn-stimulated gamma interferon- and interleukin-4-secreting cells. These studies provided information regarding the local CMI response to MoPn in mice which may prove valu able in the development of vaccination strategies for the prevention o f chlamydial genital infections.