IL21 and Autoimmunity: One possibility is that self-antigens released through adipocyte death during weight-loss could drive de novo extrafollicular responses through B cell receptor or toll-like receptor activation in the presence of cytokines (including, IFN-γ, IL-21) as postulated in autoimmunity, aging and severe SARS-CoV-2 infection [17, 18, 28, 33, 34].