Cross-reactive epitope with Klebsiella pneumoniae nitrogenase in articular tissue of HLA-B27+ patients with ankylosing spondylitis.

Synovial tissues from patients with ankylosing spondylitis or reactive arthritis were examined by an immunoperoxidase technique, using antisera to synthetic peptides representing antigens shared between HLA-B27.1 and Klebsiella pneumoniae nitrogenase. With either antiserum, all HLA-B27+ patients with synovial inflammation showed strong immunoperoxidase staining in synovial lining cells, vascular endothelium, and infiltrating inflammatory cells. These findings indicate that antigens showing cross-reactivity between HLA-B27.1 and Klebsiella nitrogenase epitopes are strongly expressed within inflamed synovial tissues of HLA-B27+ patients.