Qualitative and quantitative studies of autoantibodies to phospholipids indiabetes mellitus

Diabetes mellitus is associated with vascular and neurological complication s. We have investigated the presence of antibodies to phospholipids and to phospholipid binding plasma proteins in blood samples collected from 68 cli nically and biochemically characterized type I and type II diabetic patient s and from 252 healthy blood donor controls. Each sample was analysed for a ntibodies to three phospholipids (cardiolipin, phosphatidylserine and phosp hatidylethanolamine), the antibody isotypes (IgA, IgG and IgM), and whether antibody activity was plasma protein-dependent. Patients were considered t o have anti-phospholipid antibodies when one or more of these 18 tests was found above predetermined control values. The results of these experiments revealed an increased incidence of anti-phospholipid antibodies in diabetic patients compared with control subjects. The incidence of IgA isotype to p hosphatidylethanolamine was higher than the incidence of other isotypes to other phospholipids, and their reactivities were independent of phospholipi d-associated proteins. In addition, these antibody findings were studied fo r associations with prothrombin degradation products, activated factor VII and activated protein C, and with the incidence of diabetic complications. The anti-phosphatidylethanolamine antibody association with proliferative r etinopathy was significant.