Human lungs maintain tissue-resident memory T cells against a broad spectrum of pathogens

Lung tissue-resident memory T (TRM) cells are critical for frontline immunity, yet they undergo rapid attrition in the mouse lung. Whether this paradigm applies to humans has remained unknown. Here we present a comprehensive analysis of T cells from human lungs, characterizing the prevalence and properties of lung TRM cells specific to a broad spectrum of pathogens. Using a T cell receptor-guided approach that integrates single-cell transcriptomics with paired T cell receptor repertoire profiling, we mapped the pathogen specificity of more than 87,000 lung T cells across 40 individuals, the majority of whom harbored TRM cells specific to multiple pathogens. We confirmed that a large fraction of lung TRM clones persist in the lung for many months to years. Thus, in contrast to those of mice, human lungs retain a stable and varied pool of pathogen-specific TRM cells, suggesting that strategies to bolster these responses could provide durable protection against severe lung infections. Unlike in other tissues, lung-resident memory T cell populations are not well maintained in mice. Here the authors show that this is not the case in human lungs, where tissue-resident memory T cells specific to a variety of pathogens can persist for many years.