Beta-2-microglobulin-specific autoantibodies cause platelet aggregation and interfere with ADP-induced aggregation.

The anti-platelet activity of beta-2-microglobulin (beta 2m) specific autoantibodies isolated from sera of patients with autoimmune diseases was tested in direct and ADP-induced aggregation assays. It was established that human anti-beta 2m autoantibodies and heterologous rabbit anti-beta 2m antibodies evoke a dose-dependent aggregation of human platelets. Anti-beta 2m autoantibodies also impaired ADP-induced platelet aggregation. Antibodies with anti-beta 2m activity could be desorbed from the platelets and lymphocytes of a patients with systemic lupus erythematosus who was not thrombocytopenic. The possibility that such autoantibodies may alter platelet function is considered.