Background In terms of the presence of chronic inflammation in AS, direct and indirect evidence suggests that T cells play a role in its pathogenesis. Although the proportions of peripheral blood immune cells have been evaluated in AS, much less has been known about the relations between immune cells and bony changes in AS.
Objectives The aims of this study were to examine immune cell proportions in peripheral blood of patients with ankylosing spondylitis (AS) and to investigate relationships between immune cells, bone formation related molecules, and radiographic changes.
Methods Forty-nine AS patients and 53 age- and sex- matched healthy controls were enrolled in this study. Clinical parameters were extensively evaluated in the study subjects. CD4+ T cells, CD8+ T cells, CD56+ T cells, natural killer cells, and natural killer T (NKT) cells in peripheral blood were measured by flow cytometry. Serum levels of Dickkopf-1and bone morphogenic proteins were determined using enzyme linked immunosorbent assays. Modified Stokes AS Spinal Scores were used to assess radiographic changes.
Results Patients were found to have a significantly greater percentage of CD56+T cells than healthy controls (median 1.31% vs. 0.53%, p<0.001), whereas peripheral blood NKT cell percentages were lower in patients than in controls (median 0.07% vs. 0.10%, p=0.010). Moreover, mean CD 56+T to NKT cell ratio was markedly higher in patients. Although no significant correlations were observed between the immune cell percentages and bone formation-related molecule levels, interestingly, during 3 years of radiographic follow up, patients with a higher CD56+T to NKT cell ratio at baseline were found to develop greater radiographic changes (r =0.79, p=0.007, age and disease duration adjusted).
Conclusions An altered T cell compartment, particularly with respect to CD56+ T and NKT cells, was observed in AS patients, and could contribute to radiographic changes in AS.
Zhang L, Jarvis LB, Baek HJ and Gaston JS. Regulatory IL4+CD8+ T cells in patients with ankylosing spondylitis and healthy controls. Ann Rheum Dis 2009;68(8):1345-51.
Atagunduz P, Appel H, Kuon W, et al. HLA-B27-restricted CD8+ T cell response to cartilage-derived self peptides in ankylosing spondylitis. Arthritis Rheum 2005;52(3):892-901.
Azuz-Lieberman N, Markel G, Mizrahi S, et al. The involvement of NK cells in ankylosing spondylitis. Int Immunol 2005;17(7):837-45.
Hammond KJ and Godfrey DI. NKT cells: potential targets for autoimmune disease therapy? Tissue Antigens 2002;59(5):353-63.
Hu M, Bassett JH, Danks L, et al. Activated invariant NKT cells regulate osteoclast development and function. J Immunol 2011;186(5):2910-7.
Disclosure of Interest None Declared