Enhanced and persistent levels of interleukin ( IL) ‐17 + CD 4 + T cells and serum IL ‐17 in patients with early inflammatory arthritis

Summary Prognosis of patients with early inflammatory arthritis ( EIA ) is highly variable. The aim of this study was to compare, longitudinally and cross‐sectionally, the levels of cytokine‐expressing cells in peripheral blood ( PB ) from patients with EIA to those in established rheumatoid arthritis ( RA ) and healthy controls ( HC ). PB mononuclear cells from HC ( n  = 30), patients with EIA ( n  = 20) or RA ( n  = 38) were stimulated with phorbol myristate acetate ( PMA) /ionomycin for 3 h, and stained for cell markers and cytokines. Serum cytokines and chemokines were measured by Luminex. Patients with EIA were reassessed at 6 and 12 months. The percentage of interleukin ( IL) ‐17 + interferon ( IFN)‐ γ − CD 4 + T cells [T helper type 17 ( T h17)] was increased in RA and EIA   versus   HC . Serum IL ‐1β, IL ‐2, IL ‐4 IL ‐17 and macrophage inflammatory protein ( MIP) ‐1α were increased in RA and EIA   versus   HC . IL ‐1Ra, IL ‐15 and IFN ‐α were increased in EIA   versus   HC . IL ‐6 and tumour necrosis factor ( TNF)‐ α was increased in RA but not EIA   versus   HC . Disease activity scores in EIA patients improved over 12 months' treatment. Th17 percentage at baseline was correlated with both rheumatoid factor ( RF ) titre and functional deficit at 12 months. Baseline levels of serum granulocyte–macrophage colony‐stimulating factor ( GM‐CSF) , IL ‐6 and IL ‐8 were correlated with Larsen score at 12 months. There were no significant changes in cytokine‐expressing CD 4 + T cells over time, although the percentage of IL ‐6 + monocytes increased. IL ‐17 + CD 4 + T cells and serum IL ‐17 levels are increased in EIA . IL ‐6‐expressing monocytes increase during the first year of disease, irrespective of disease‐modifying anti‐rheumatic drug ( DMARD) therapy. We observed incomplete clinical responses, suggesting EIA patients need more intensive early therapy.