IL21 and hepatic granuloma: Our previous paper has demonstrated that Tfh cells have a key role in the formation of hepatic granuloma in Sjaponicum‐infected mice.12 Although some studies raised the possibility that IL‐4 and/or IL‐21 produced by Tfh cells may contribute to Tfh cell‐mediated granuloma formation in schistosome‐infected mice,20, 21, 22 the exact mechanisms of how Tfh cells promote the granuloma formation remain unclear.