CD4 and psoriasis vulgaris: Interestingly, researcher found that two-thirds of patients with moderate-to-severe plaque psoriasis harbor CD4+ and/or CD8+ T cells specific for LL-37 infiltrating lesioned skin, which produce IFN-γ (Th1 cytokines), and CD4+ T cells also produce Th17 cytokines (IL-17, IL-21, and IL-22) [23].