Frequency and phenotype of T helper 17 cells in peripheral blood and synovial fluid of patients with reactive arthritis

Objective.To analyze the frequency and phenotype of peripheral blood mononuclear cells (PBMC) and synovial fluid mononuclear cell (SFMC) T helper (Th)17 cells in reactive arthritis (ReA).Methods.T cell surface phenotype and cytokine production were measured following stimulation, using 8-color flow cytometry.Results.The percentages of interleukin 17 (IL-17)–positive CD4+ T cells were increased in SFMC of patients with ReA compared with PBMC. All IL-17+ cells were CD4+CD45RO+; in SFMC most expressed CCR6, but only 50% expressed CCR4. IL-17+ cells sometimes coexpressed IL-22 and/or interferon-γ, but not IL-10.Conclusion.These data support the hypothesis that Th17 cells are involved in ReA pathogenesis.