Annexin V autoantibodies in rheumatoid arthritis.

OBJECTIVE To investigate the occurrence of anti-annexin V autoantibodies in sera of patients with rheumatoid arthritis to assess involvement with the disease and any relation to glucocorticoid treatment. METHODS Anti-annexin V antibodies were measured by an enzyme linked immunosorbent assay (ELISA) which used the purified human recombinant protein as antigen. RESULTS Concentrations of anti-annexin V autoantibodies, predominantly of the IgG class, were significantly raised in sera from patients with rheumatoid arthritis compared to normal controls. This was not correlated with other indices of disease activity such as erythrocyte sedimentation rate or C reactive protein and was unrelated to glucocorticoid treatment. CONCLUSIONS Extracellular annexin V provides an antigenic stimulus for autoantibody production and its in vivo expression is independent of glucocorticoid control. Such autoantibodies may have a detrimental role in the arthritic condition by interfering with putative functions of annexin V, including collagen type II binding, inhibition of phospholipase A2 activity, and Fc receptor activity.