Abstract: [Abstract] Objective To study the role of the imbalance of Th1/Th2 and Th1/Th2 cytokines in the pathogenesis of AS.Methods 30 subjects patients with AS and and 20 subjects normal controls had been chosen. Enzyme linked immunosorbent assay (ELISA) was used to measure the levels of TNF-α and IL-10 in the serum and synovial fluid. Three-color flow cytometric analysis was employed for surface antigens (CD3, CD4) of Th cells and intracellular cytokines (IFN-γ/IL-4) of Th1/Th2 in the peripheral blood of patients with AS and normal controls.Result The TNF-α and IL-10 serum levels in patients with AS were all significantly higher than in normal controls(P<0.05); The synovial fluid level of TNF-α was significantly higher than the serum level (P<0.05), The synovial fluid level of IL-10 was not significantly different from the serum level (P>0.05); The percentage of Th1 and Th2 cells in the peripheral blood of patients with AS were not significantly different from normal controls (P>0.05),The percentage of Th1 cells in the peripheral blood of patients with AS was significantly higher than normal controls, The rate of Th1/Th2 was significantly higher than in normal controls (P<0.05)；The serumlevel of TNF-α correlated significiently with ESR, CRP. There wasn’t significant correlation between the serum level of IL-10、the percentage of Th1 cells (or Th2 cells) 、 the rate of Th1/Th2 and ESR, CRP (P>0.05). Conclusion There is an imbalance in Th1/Th2 in the peripheral blood of patients with AS, and towards Th1.

Key words: Spondylitis, ankylosing, Th1 cells, Th2 cells, cytokines, three-color flow cytometric analysis