Depletion of CD8+ cells abolishes memory in acquired immunity against Chlamydia pneumoniae in BALB/c mice

Immunology. 1999 Jul;97(3):490-6. doi: 10.1046/j.1365-2567.1999.00809.x.

Abstract

The importance of T cells in Chlamydia pneumoniae infection in mice was assessed by comparing wild-type BALB/c mice with nude mice and mice depleted in vivo of either CD4+ or CD8+ T cells. Whereas wild-type mice cleared the primary infection in 3 weeks, nude mice were only able to restrict the infection and could not clear it during the observation period of 56 days. Nude mice exhibited a greater number of macrophages in their lungs and the pulmonary cells secreted a higher level of tumour necrosis factor-alpha (TNF-alpha) than wild-type mice. Depletion of CD4+ cells did not change the overall infection kinetics of the primary infection. However, depletion of CD8+ cells resulted in a slightly impaired clearance of the bacteria in the late stages of primary infection. To assess the role of the two T-cell subsets in the acquired immunity that develops during primary infection in wild-type BALB/c mice, in vivo depletions were performed during reinfection. Prior to reinfection, immunocompetent wild-type mice were infected and natural immunity was allowed to form. During reinfection, depletion of CD4+ cells did not have any effect on infection kinetics, whereas depletion of CD8+ cells abolished the protection, reverting the infection kinetics and bacterial load to the same levels found in wild-type mice during primary infection. These results show that T cells are necessary for clearing C. pneumoniae infection in mice. Furthermore, whereas neither of the two main T-cell subsets, separately, were essential for clearance of primary infection, the induced protective immunity was strongly CD8 dependent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD4-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / immunology*
  • Cell Division / immunology
  • Chlamydia Infections / immunology*
  • Chlamydophila pneumoniae*
  • Cytokines / biosynthesis
  • Female
  • Immunity, Cellular
  • Immunologic Memory*
  • Lung / immunology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude

Substances

  • Cytokines