Although there were few numbers of cells producing IL-17A or IFN-γ in PBS-injected control ears, significant accumulations of the IL-17A+ and IL-17A+IFN-γ+CD4+ T-cell populations were observed in the IL-23–injected ear, as observed in psoriatic dermis of patients with psoriasis.59 This evidence concerns the gene CD4 and psoriasis.