Significance of glomerular deposition of apolipoprotein (a) in various glomerulopathies.

Apolipoprotein (a) [apo(a)] may interfere with the fibrinolytic system because of its structural similarity to plasminogen. In the present study, we evaluated the effect of glomerular deposition of apo(a) on coagulation and fibrinolysis in patients with glomerular diseases. Twenty-four patients (13 males and 11 females) with various glomerulopathies were studied. We examined renal biopsy specimens for the presence of apo(a), and investigated the relationship between the glomerular deposition of apo(a) and coagulation and fibrinolysis within the glomeruli. The patients who exhibited the deposition of apo(a) (group A) had a significantly higher incidence of deposition of apo B-100 and low-density lipoprotein (LDL) receptor, and a significantly lower incidence of deposition of plasmin-alpha 2-plasmin inhibitor complexes (PIC) and tissue-type plasminogen activator than did patients without apo(a) deposition (group B). Patients in group A had a significantly higher level of serum total cholesterol and lipoprotein (a) than did patients in group B. Plasma levels of PIC and D-dimer in group A were significantly lower than those in group B. The plasma level of thrombin-antithrombin III complexes in group A was significantly higher than that in group B. These findings suggest that glomerular apo(a) deposition plays a part in coagulation and fibrinolysis within the glomeruli in patients with glomerular diseases.