[beta2-Microglobulin in ankylosing spondylitis and in Reiter's syndrome (author's transl)].

In patients with ankylosing spondylitis (AS) the plasma level of beta2-microglobulin (beta2m) is signficantly higher (1.95 +/- 0.48 mg/l) than in osteoarthritis (1.48 +/- 0.47 mg/l). In Reiter's syndrome the level of beta2m is also higher than in controls, but the paucity of results do not allow definite conclusions. The plasma level of beta2m in AS and in Reiter's syndrome is not related to the presence of HLA B 27 antigen, neither to other biological parameters as sedimentaton rate, blood cell counts, electrophoresis of plasma proteins. In rheumatoid arthritis the plasma level of beta2m is 2,67 +/- 0.84 mg/l, significantly higher than in osteoarthritis or in AS even without any association with Sjögren's syndrome. In synovial fluid, the beta2m level is closely related to the degree of inflammation, suggesting a local production of this substance.