Frequency of interleukin-17+ and interleukin-22+CD4+ T cells in the peripheral blood mononuclear cells of patients with psoriatic arthritis patients with psoriasis and healthy controls. The frequency of interleukin 17 (IL-17)-positive CD4+ T cells (A) and IL-22-positive CD4+ T cells (C) in patients with psoriasis (Ps) or psoriatic arthritis (PsA) and healthy controls. The percentages of total CD4+ T cells are shown. Typical examples of intracellular staining of IL-17 (B) and IL-22 (D) are also shown after gating for CD3+CD4+ T cells. * p<0.05, **p<0.01, ***p<0.001 FSC = Forward Scatter.