ROLE OF BETA(2)-GLYCOPROTEIN-I IN THE ANTICARDIOLIPIN ANTIBODY-AFFINITY FOR PHOSPHOLIPID IN AUTOIMMUNE-DISEASE

The binding capacity to cardiolipin and the functional affinity of aff inity-purified anticardiolipin (aCL) IgG of patients with autoimmune d isease have been compared with those of individuals with malaria and a cquired immunodeficiency syndrome (AIDS). The binding of autoimmune Ig G aCL was enhanced gradually by the incorporation of increasing amount s of beta(2)-glycoprotein I (beta(2)GPI) into the assay, in contrast t o that of patients with infectious diseases. In addition, there were s ignificant reductions of functional affinity in autoimmune disease, bu t not in malaria or in AIDS. These results indicate that beta(2)GPI re quirement for binding to the target antigen varies inversely with func tional affinity in autoimmune disease when beta(2)GPI was present, and suggest that IgG aCL are more heterogeneous in this type of disorder than in patients with infectious disease.