HLA-B27 and Ankylosing Spondylitis

Abstract

Ankylosing spondylitis (AS) is a chronic inflammatory disease with potential disabling outcomes. Clinically, patients presented with inflammatory lower back pain, enthesis and alternated buttock pain (van der Linden & van der Heijde, 1998). Bernard Corner (16661698) was the first physician who published the clinical features of AS in his medical thesis (Baker & Weisman, 2006). In the late 19th century, 3 independent physicians: Marie, Strupell, and Bechterew were able to describe the specific radiographic change in those patients by the help of the invention of radiology (Bywaters, 1983). But, still clinically, the boundary between AS and rheumatoid arthritis was unclear. Thanks to the discovery of rheumatoid factor which was strongly associated with rheumatoid arthritis, the distinction between these two arthritides became crystal clear. In those patients with inflammatory lower back pain and seronegative for rheumatoid factor, the diagnosis of ankylosing spondylitis became more popular in the early 1960 (Zeider et al., 2011). In 1963, American Rheumatism Association proposed a new nomenclature and classification for the rheumatic diseases. In this new edition, AS was specified as a complete different disease entity from rheumatoid arthritis (Blumberg et al., 1964). In addition to those different clinical characteristics, such as bone proliferation in enthesis site and sacroiliitis, in AS patients from those of patients with rheumatoid arthritis, AS is also known for its high association with HLA-B27. It has been known for more than 30 years since this association was discovered at 1973 (Schlosstein, 1973; Brewerton et al., 1973), although afterward, researchers found several HLA antigens were associated with other diseases (Invernizzi, 2011; McElroy, 2011; Piga, 2011), the strongest of any HLA antigens associated with human disease is HLA-B27 molecule. Hence, the roles of HLA-B27 in the pathogenesis and clinical manifestation of ankylosing spondylitis were among most frequent discussed topics in the past three decades.