Ankylosing spondylitis: a β2m–deposition disease?

To explain the strong association between HLA-B27 and ankylosing spondylitis, we suggest that the release of β2-microglobulin (β2m) from a subpopulation of cell surface-expressed HLA-B27 molecules leads to β2m-deposition within synovia and to the initiation of an inflammatory process, which culminates in destructive spondyloarthropathy.