Editorial: Exploring adaptive immunity in ruminants and humans: a one health perspective

A core theme of this collection is the detailed characterization of adaptive immune responses to specific pathogens and their underlying cellular machinery. In a pioneering study, Yu et al. delve into the oftenoverlooked realm of subclinical mastitis caused by Staphylococcus chromogenes. Their work provides the first evidence that γδ T cells are not merely bystanders but active participants in the immune defense of the bovine mammary gland during this chronic infection. The expansion of γδ T cells expressing CD44 and their robust production of IFN-γ, IL-17, and cytotoxic molecules (GZMB) reveal a critical, first-line role for these unconventional lymphocytes. Simultaneously, the observed reduction in CD4⁺CD8⁺ double-positive T cells in the milk points to a potential immunological vulnerability, suggesting a state of exhaustion that may predispose animals to more severe, clinical mastitis. Beyond veterinary applications, these findings have implications for human health, as Staphylococcus species are also important human pathogens.