The development of Chlamydia pneumoniae-specific cell-mediated immunity was
studied during a primary C. pneumoniae infection. The immune response was
detected as positive lymphocyte proliferation and secretion of interferon g
amma. C. pneumoniae-induced activation of both CD4(+) and CD8(+) T cells wa
s detected in the early phase of infection, but activation of only CD4(+) T
cells was detected in the later stage.