CD4 and psoriasis: As shown in Figure 3A,B, in CD3+ cells of IMQ‐induced psoriasis‐like skin lesions, CD4+IL‐17A+ T cells were significantly increased (12.760 ± 3.12% vs. 0.250 ± 0.082% in control skin lesions); while in astilbin‐treated mice, IL‐17A+ cells were significantly reduced in a dose‐dependent manner (5.410 ± 2.260% in the AL group and 1.575 ± 0.410% in the AH group).