Chronic endometritis—Plasmacytes, B cells, and the third-party pulling strings behind the scenes: commentary on Yang L. et al. An endometrial immune atlas across the female menstrual cycle reveals lymphoid aggregates compromise pregnancy. Nat. Commun

The study by Yang et al. (https://doi.org/10.1038/s41467-026-76937-y) redefines chronic endometritis as an immunopathological mess driven not only by endometrial stromal plasmacytes and B cells but also by the 'bad company' of co-infiltrating follicular helper T-like cell subsets. These three aberrant local immunocompetent cell types in chronic endometritis might work hand in glove, potentially deteriorating the mucosal immunity and integrity required for successful pregnancy.