IL21 and obesity due to melanocortin 4 receptor deficiency: As B cells are involved in the inflammatory landscape present in obesity, undergoing expansion in adipose tissues from mice fed a high‐fat diet, where they can activate T cells and macrophages (Winer et al, 2014; Zatterale et al, 2019), they have the potential to receive IL‐21, IFN‐y, and TLR7 stimulation, priming them to a DN2 B‐cell fate.