Cell-mediated immune response during primary Chlamydia pneumoniae infection.

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 gamma. C. pneumoniae-induced activation of both CD4(+) and CD8(+) T cells was detected in the early phase of infection, but activation of only CD4(+) T cells was detected in the later stage.