Turbinate-homing IgA-secreting cells originate in the nasal lymphoid tissues.

Nasal vaccination elicits a humoral immune response that provides protection from airborne pathogens, yet the origins and specific immune niches of antigen-specific IgA-secreting cells in the upper airways are unclear. Here we define nasal glandular acinar structures and the turbinates as immunological niches that recruit IgA-secreting plasma cells from the nasal-associated lymphoid tissues (NALTs). Using intact organ imaging, we demonstrate that nasal vaccination induces B cell expansion in the subepithelial dome of the NALT, followed by invasion into commensal-bacteria-driven chronic germinal centres in a T cell-dependent manner.