Humans with dysfunctional Bruton's tyrosine kinase (Btk) are highly susceptible to bacterial infections. Compelling evidence indicates that Btk is essential for B cell-mediated immunity, whereas its role in myeloid cell-mediated immunity against infections is controversial. In this study, we determined the contribution of Btk in B cells and neutrophils to host defense against the extracellular bacterial pathogen Klebsiella pneumoniae, a common cause of pulmonary infections and sepsis. Btk-/- mice were highly susceptible to Klebsiella infection, which was not reversed by Btk re-expression in B cells and restoration of natural antibody levels. Neutrophil-specific Btk deficiency impaired host defense against Klebsiella to a similar extent as complete Btk deficiency. Neutrophil-specific Btk deficiency abolished extracellular reactive oxygen species production in response to Klebsiella. These data indicate that expression of Btk in neutrophils is crucial, while in B cells, it is dispensable for in vivo host defense against K. pneumoniae.
Original languageEnglish
JournalJournal of innate immunity
Early online date2022
Publication statusE-pub ahead of print - 2022


  • Bruton's tyrosine kinase
  • Innate immunity
  • Klebsiella pneumoniae
  • Neutrophils
  • Reactive oxygen species

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