Decreased levels of serum soluble HLA class I antigens in HLA-B27 positive spondyloarthropathies

Human leucocyte class I antigens (HLA-I) are expressed on the surface of all nucleated cells but can also be found in soluble forms. These soluble HLA-I (sHLA-I) molecules can be produced by either membrane shedding, proteolysis of the intact heavy chain, or by alternative splicing.1 They have been implicated in regulatory functions and have immunomodulatory properties.2 Increased levels of sHLA-I were found during graft rejections, in various infectious (cytomegalovirus, hepatitis B or C, HIV infection, active tuberculosis) and autoimmune diseases.3–6 In systemic lupus erythematosus and rheumatoid arthritis, levels of sHLA-I antigens correlate with disease activity.4,6 Spondyloarthropathies (SpA) are conditions closely linked to HLA-B27, a class I antigen. Thus, in this study, we evaluated the serum concentrations of sHLA-I antigens in a large cohort of patients with SpA. One hundred and twenty three patients …