Interleukin-35 takes the 'B' line

Regulatory B cells exert an immunosuppressive role by secreting the cytokine interleukin-10 (IL-10). Two studies have now identified B cell derived IL-35 as both an inducer and a mediator of regulatory B cell function. IL-35 switched off inflammation in mouse models of autoimmunity, whereas its absence in B cells in mice enhanced survival after Salmonella enterica serovar Typhimurium infection. IL-35 could therefore be targeted for treating human autoimmune and infectious disease.