IL9 and eosinophilic granulomatosis with polyangiitis: In EGPA patients, mepolizumab combined with standard treatment led to prolonged remission and less steroid use.341 IL-12 and IL-23 share the signature p40 subunit, and an anti-IL-12/23 p40 antibody (p40 mAb) interferes with Tfh cell differentiation and inhibits proinflammatory cytokine secretion.