MR16-1-treated PD-1-cKO mice exhibited significant improvement in clinical manifestations of IMQ-induced psoriasis-like dermatitis compared to IgG Ctrl-treated PD-1-cKO mice (ear swelling change from the baseline on day 7, 7.8 ± 1.5 μm vs. 16.3 ± 1.4 μm, P = 0.0012 by two-way ANOVA; and PASI score at day 7, 4.3 ± 0.2 vs. 8.2 ± 0.7, P < 0.0001 by two-way ANOVA). This evidence concerns the gene PDCD1 and psoriasis.