Neutrophils, the most abundant leukocytes in human blood, have multifaceted roles in health and disease. Here we assembled a single-cell atlas of human neutrophils (SCAHN) by integrating transcriptome data from 1 million human neutrophils from 781 samples and 43 independent datasets. Using SCAHN, we identified multiple neutrophil subsets with distinct functions across tissues and robust changes in gene expression and subset proportions in infection, cancer, immune suppression and sex differences at single-cell resolution. Cross-species reference mapping of mouse and nonhuman primate neutrophils onto SCAHN revealed both conserved and species-specific features. Using 17,023 bulk blood transcriptome profiles from 40 datasets, we found that neutrophil-specific signatures predicted mortality in acutely ill patients at presentation, were associated with cancer diagnosis and survival, and correlated with metabolic dysfunction and long-term all-cause mortality. Our study highlights how neutrophil biology can improve immune risk stratification and develop effective diagnostic and therapeutic strategies. Khatri and colleagues assembled a single-cell atlas of 1 million human neutrophils based on the integration of 43 independent single-cell transcriptome datasets to define multiple neutrophil subsets with distinct functions across tissues and disease states.
