ENRICHMENT OF ANTIBODIES AGAINST PHOSPHOLIPIDS IN CIRCULATING IMMUNE-COMPLEXES (CIC) IN THE ANTIPHOSPHOLIPID SYNDROME (APLS)

The aim of this study was to analyse and characterize immunoglobulins in CIC and serum from patients with anti-cardiolipin antibodies. CIC f rom five patients were isolated by gradient centrifugation and gel fil tration. The distribution between serum and CIC of immunoglobulin reac tivity against different phospholipids was determined. Serum and CIC c ontained antibodies against cardiolipin and other negatively charged p hospholipids. The relative concentration of these antibodies was highe r in the immune complexes than in corresponding sera, and the avidity of antibodies in immune complex form was higher. The presence of high concentrations of antibodies to negatively charged phospholipids in CI C iom patients with anti-cardiolipin antibodies could be of pathogenic significance in APLS by conferring characteristics to the complexes o f importance for binding to membrane components. This could have speci al implications with regard to platelet and complement activation, thr ombocytopenia and thrombophilia.