Nature Communications, Published online: 11 September 2026; doi:10.1038/s41467-026-77588-9 Environmental cues, such as pH, determine cellular differentiation and function, including that of immune cells. Here the authors identify SLC4A7, a Na + /HCO3–cotransporter as a critical and specific regulator of plasmablast differentiation genetic deletion of which in mice impairing antibody responses.