Differential expression of interleukin‐2 by anti‐ CD 3‐stimulated peripheral blood mononuclear cells in patients with psoriatic arthritis and patients with cutaneous psoriasis

Summary The differences in systemic T ‐cell responses between patients with psoriatic arthritis ( P s A ) and patients with cutaneous psoriasis ( P s) are still largely unknown. To determine differential features that could be used to distinguish P s A from P s, we compared the cytokine secretion profile of circulating T cells in patients with P s A , patients with cutaneous P s and control subjects. We determined T h1, T h2 and T h17 cytokine secretion of anti‐ CD 3‐stimulated peripheral blood mononuclear cells ( PBMC s) using a cytokine bead array. Normality of data distribution was assessed by the S hapiro– W ilk test, and statistical significance was calculated by the M ann– W hitney test. Phenotypic characterization of circulating T cells was performed by fluorescence‐activated cell sorting analysis. We found that the major systemic differences distinguishing P s A from cutaneous P s were the increased secretion of interleukin ( IL )‐2 by α‐ CD 3‐stimulated PBMC s and a higher percentage of circulating CD 3+ T cells expressing the proliferation marker CD 71 in P s A . These results indicate IL ‐2 as a possible biomarker of P s A , and suggest a role of circulating T cells with high proliferative capacity in the pathogenesis of P s A .