Intracytoplasmic cytokine expression and T cell subset distribution in the peripheral blood of patients with ankylosing spondylitis.

Objective: To determine the role of inflammatory mediators in the pathogenesis of ankylosing spondylitis (AS), we investigated peripheral blood lymphocyte subsets and their intracellular cytokine production.

Methods: The percentages of T and B lymphocytes, natural killer (NK) cells, activated T lymphocytes, CD4+ T helper (Th), and CD8+ T cytotoxic (Tc) cells were determined by flow cytometry in 42 patients with AS compared to 52 healthy controls. In order to assess circulating Th1/Th2 and Tc1/Tc2 subsets, we used a whole-blood cytometric assay based on the intracellular interferon-gamma, interleukin 4 (IL-4), and IL-10 expression of the cells.