Ankylosing spondylitis syndrome in patients without HLA-B27

We wish to present in this paper the main clinical, roentgenological and immunogenetic characteristics of our patients with the ankylosing spondylitis syndrome, who do not possess the HLA-B27 antigen. Of 553 patients permanently treated in the Ward for Rheumatic Diseases of the Medical Faculty in Zagreb, 16 patients (7 women and 9 men) have been found who do not have the HLA-B27 antigen. Their average age was 39.6 (men: 46; women: 33; range: 25-66) years. The diagnosis of ankylosing spondylitis had been made on the basis of the Rome criteria (1) and that of sacroiliitis on the criteria of Hart and Robinson (2). HLA antigens were determined on the peripheral blood lymphocytes using the microcytotoxic test according to Terasaki and McClelland (3).