CD4 and viral infectious disease: TCR stimulation is crucial for the effective induction of EZH2 expression in CD4+ T cells.33,63 The enhanced strength and duration of the interaction between TCR and pMHC favors TFH differentiation,64 which may partially explain the elevated EZH2 expression levels observed in TFH cells compared to those of their TH1 counterparts following an acute viral infection.