CD4+ T cells mediate antibody-independent acquired immunity to pneumococcal colonization

Proc Natl Acad Sci U S A. 2005 Mar 29;102(13):4848-53. doi: 10.1073/pnas.0501254102. Epub 2005 Mar 21.

Abstract

Acquired immunity to Streptococcus pneumoniae (pneumococcus) has long been assumed to depend on the presence of anticapsular antibodies. We found, however, that colonization with live pneumococci of serotypes 6B, 7F, or 14 protected mice against recolonization by any of the serotypes and that protection from acquisition of a heterologous or homologous strain did not depend on anticapsular antibody. Further, intranasal immunization by live pneumococcal colonization or by a killed, nonencapsulated whole-cell vaccine protected antibody-deficient mice against colonization, suggesting independence of antibodies to any pneumococcal antigens. Protection by intranasal immunization with whole-cell vaccine was completely abrogated in T cell-deficient mice, and in mice that were congenitally deficient in CD4(+) T cells or depleted of these cells at the time of challenge. In contrast, mice congenitally deficient in, or depleted of, CD8(+) T cells were fully protected. Protection in this model was observed beyond 2 months after immunization, arguing against innate or nonspecific immune mechanisms. Thus, we find that immunity to pneumococcal colonization can be induced in the absence of antibody, independent of the capsular type, and this protection requires the presence of CD4(+) T cells at the time of challenge.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Administration, Intranasal
  • Animals
  • CD4-Positive T-Lymphocytes / immunology*
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Immunity, Cellular*
  • Mice
  • Mice, Inbred C57BL
  • Pneumococcal Infections / prevention & control*
  • Species Specificity
  • Streptococcal Vaccines / administration & dosage
  • Streptococcal Vaccines / immunology*
  • Streptococcus pneumoniae / immunology*
  • Time Factors

Substances

  • Streptococcal Vaccines