Antibodies against phosphatidyl-inositol, an phospholipid derived from glycerol, belong to the group of anti-phospholipid antibodies specific for phospholipids such as cardiolipin, phosphatidyl- serine, -etha- nolamin, -choline, sphingomyelin and phosphatidic acid. Phospholipids are components of biological membranes.
Anti-phospholipid antibodies are frequently found in sera of patients with systemic lupus erythematosus (SLE) and related diseases. The occurrence of anti-phospholipid antibodies in patients with SLE and related diseases is typical for a secondary anti-phospholipid syndrome (APS). In contrast, anti- phospholipid antibodies in patients with no other autoimmune diseases characterize the primary APS.
Many studies have shown a correlation between these autoantibodies and an enhanced incidence of thrombosis, thrombocytopenia and habitual abortions (as a consequence of placental infarction). The exact mechanisms by which pathogenic anti-phospholipid antibodies induce thrombosis is not yet revealed fully.