IL21 and fungal infectious disease: Furthermore, the lack of mucocutaneous candidiasis in patients with impaired signaling via receptors for IL-6 (IL6R, IL6ST mutations [9, 11, 50, 62, 63]; anti-IL-6 autoantibodies [64]), IL-23 (biallelic IL23R variants) [65] or IL-21 (biallelic IL21 or IL21R variants) [66] argues that individually these cytokines are not required for the STAT3-mediated generation of human Th17 cells and host defense against fungal infections.