Evidence for a specific B27-associated cell surface marker on lymphocytes of patients with ankylosing spondylitis

Abstract

THE strong association of HLA-B27 with ankylosing spondylitis (AS) as well as an increased frequency of B27 in other seronegative arthropathies is well documented^1–4. Nevertheless, the significance and the molecular basis of this remarkable association is still unknown. Ebringer et al.⁵⁻⁷ reported that Klebsiella pneumoniae was present in the faeces of patients with AS more frequently than in those of healthy controls, and that there seemed to be some cross-reactivity between HLA-B27-positive lymphocytes and Klebsiella antigen. It is possible, therefore, that an infectious agent, probably an enteric organism, is involved in the pathogenesis of AS. We have therefore decided to examine the in vitro proliferative responses of peripheral blood lymphocytes to Klebsiella and to several enteric organisms. To examine the possibility of cross-reactivity between B27 and Klebsiella antigen, we raised antisera in rabbits against various isolates of Klebsiella and tested the cytotoxicity of these antisera on lymphocytes of AS patients and of normal controls. The results presented here strongly suggest that Klebsiella antigens cross-react with a gene product closely associated with HLA-B27 or with a Klebsiella-associated B27 antigen in AS patients.