B-1a and B-1b cells exhibit distinct developmental requirements and have unique functional roles in innate and adaptive immunity to S. pneumoniae

Immunity. 2005 Jul;23(1):7-18. doi: 10.1016/j.immuni.2005.04.011.


B-1a and B-1b lymphocytes were found to exhibit specialized roles in providing immunity to Streptococcus pneumoniae and differ dramatically in their developmental requirements. Transgenic mice overexpressing CD19 (hCD19Tg) generated B-1a cells and natural antibodies that provided protection during infection, while CD19-deficient (CD19(-/-)) mice lacked B-1a cells, lacked natural antibodies, and were more susceptible to infection. By contrast, pneumococcal polysaccharide (PPS) immunization protected CD19(-/-) mice during lethal challenge, whereas hCD19Tg mice remained unprotected. This resulted from differences in the B-1b subset: the key population found to produce protective PPS-specific antibody in both wild-type and CD19(-/-) mice. Thus, CD19(-/-) mice generated B-1b cells and protective adaptive PPS-specific antibody responses, whereas hCD19Tg mice lacked B-1b cells and adaptive PPS-specific antibody responses. This reciprocal contribution of B-1a and B-1b subsets to innate and acquired immunity reveals an unexpected division of labor within the B-1 compartment that is normally balanced by their coordinated development.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Bacterial / genetics
  • Antibodies, Bacterial / immunology*
  • Antigens, CD19 / genetics*
  • B-Lymphocyte Subsets / immunology*
  • Cell Differentiation
  • Immunity, Innate / genetics
  • Immunity, Innate / immunology*
  • Immunization
  • Mice
  • Mice, Transgenic
  • Mutation
  • Pneumococcal Infections / immunology*
  • Pneumococcal Infections / prevention & control
  • Polysaccharides, Bacterial / immunology*
  • Streptococcus pneumoniae / immunology*


  • Antibodies, Bacterial
  • Antigens, CD19
  • Polysaccharides, Bacterial
  • pneumococcal polysaccharide, type III