Urinary fibrin-fibrinogen degradation products and intraglomerular fibrin-fibrinogen deposition in various renal diseases

Analysis of urinary and circulating FDP subfragments and subunits: application of the western-blot technique

We applied the Western-blot technique for qualifying fibrin/fibrinogen degradation products (FDP) subfragments and subunits. With this technique we examined urine or serum samples from patients with glomerulonephritis and disseminated intravascular coagulation (DIC), in order to observe how primary or secondary fibrinolysis functioned under these pathological conditions. We also tested the antigenic recognition of several FDP antibodies with this technique. The results obtained were as follows: 1) FDP in serum samples from patients with DIC consisted of both fibrinogenolytic and fibrinolytic products; 2) Fibrinolysis was predominant in the serum from one patient with Henoch-Schönlein purpura nephritis, and its level increased after fibrinolytic therapy with urokinase; 3) Fibrinogen and fibrin polymers were always the major components of urinary FDP, although fibrinolytic products such as subfragment D-D dimer were detected in patients with glomerular disease and increased in acute exacerbation; 4) Anti-FDP D-D dimer monoclonal antibody (DD 3B6), which is usually considered to react specifically with cross-linked fibrin derivatives, also seemed to have cross-reactivity with non-crosslinked fibrin derivatives.

Fragments of urinary fibrin/fibrinogen degradation products and cross-linked fibrin degradation products in various renal diseases

In children with several kinds of glomerular disease, fragments of fibrin/fibrinogen degradation products (FDP) and cross-linked fibrin degradation products (XLFDP) in the urine were investigated by autoradiography using western blotting method. Results were compared with selectivity of proteins observed in cases of proteinuria, or with histological findings. Patients with nephrotic syndrome exhibited slightly increased amount of urinary FDP, consisted mainly of X and Y fragments. On the other hand, in cases of proliferative glomerulonephritis, such as acute glomerulonephritis, purpura nephritis, Ig A nephropathy, systemic lupus erythematosus, or hemolytic uremic syndrome, increased FDP, including XLFDP, was detected in the urine. In these cases, FDP was consisted mainly of fragments X, Y, and D-dimer, and could not be correlated with the degree of mesangial proliferation or with urinary protein selectivity. It was concluded that the increased urinary FDP and XLFDP were derived not only from filtration of plasma fibrinogen or FDP, but also from fibrinolysis of intraglomerular fibrin deposits.

Urinary crosslinked fibrin degradation products in glomerular disease

Urinary levels of crosslinked fibrin degradation products (XLFDP) in glomerular disease were measured by radioimmunoassay using monoclonal antibodies. The majority of patients with crescentic glomerulonephritis or focal segmental sclerosis/hyalinosis showed increased levels of urinary XLFDP. Mild to moderately increased levels were seen in some patients with other forms of glomerulonephritis. In focal segmental sclerosis/hyalinosis or membranous nephropathy, however, XLFDP levels correlated with proteinuria and the ratio of XLFDP to proteinuria was lower than in crescentic glomerulonephritis. Although isolated urinary XLFDP is not necessarily an index of intraglomerular coagulation and fibrinolysis, the ratio of XLFDP to proteinuria may provide a useful marker for active glomerular lesions as crescents and/or intraglomerular coagulation and fibrinolysis.