In psoriasis, myeloid dendritic cells secrete IL12 and IL23, prompting T cells to differentiate into Th1 and Th17 cell subtypes; Th1 cells secrete TNF-α and IFN-γ, which promote the activation and proliferation of keratinocytes and the expression of adhesion molecules such as intercellular adhesion molecule 1 (4); Th17 cells secrete IL17 and IL22 to promote the proliferation of keratinocytes and angiogenesis in the lesion (5). The gene discussed is IL17A; the disease is psoriasis.