Bystander Activation of Pulmonary Trm Cells Attenuates the Severity of Bacterial Pneumonia by Enhancing Neutrophil Recruitment

Chenghao Ge, Ian R. Monk, Angela Pizzolla, Nancy Wang, James G. Bedford, Timothy P. Stinear, Glen P. Westall, Linda M. Wakim

Research output: Contribution to journalArticleResearchpeer-review

16 Citations (Scopus)


Tissue-resident memory T (Trm) cells are described as having a “sensing and alarming” function, meaning they can rapidly release cytokines in response to local cognate antigen recognition, which in turn, draws circulating immune cells into the tissue. Here, we show noncognate, bystander activation can also trigger the sensing and alarming function of pulmonary CD8+ Trm cells. Virus-specific CD8+ Trm cells lodged in the lung parenchyma, but not memory CD8+ T cells located in the vasculature, rapidly synthesize interferon γ (IFN-γ) following the inhalation of heat-killed bacteria or bacterial products, a process driven by interleukin-12 (IL-12)/IL-18 exposure. We show that a respiratory bacterial infection leads to bystander activation of lung Trm cells that boosts neutrophil recruitment into the airways and attenuates the severity of bacterial pneumonia. These data reveal that lung Trm cells have innate-like properties, enabling amplification of inflammation and participation in noncognate responses to bacterial infections.

Original languageEnglish
Pages (from-to)4236-4244.e3
Number of pages12
JournalCell Reports
Issue number13
Publication statusPublished - 24 Dec 2019


  • bystander activation
  • Resident memory T cell

Cite this