Different flavors of IL-21 in regulation of intestinal IgA to commensals

IL-21 has been shown to regulate IgA production. However, how it regulates gut microbiota and intestinal homeostasis through regulation of IgA is still not fully understood. A study by Cho et al in this issue of Mucosal Immunology demonstrates that IL-21 promotes intestinal IgA responses to atypical commensals to reshape the mucosal immunity and microbiota.