The increased serum levels of IL-2 were associated with other types of psoriasis, but not with psoriasis vulgaris (Supplementary Table 1, Others: SMD = 0.89, 95% CI 0.24 to 1.52, I2 = 81.9%; Psoriasis vulgaris: SMD = 0.57, 95% CI 0.16 to 0.98, I2 = 0%). Here, IL2 is linked to psoriasis.