URINARY FIBRIN/FIBRINOGEN DEGRADATION PRODUCTS (FDP) AND GLOMERULONEPHRITIS

Relationship between urinary fibrinogen degradation products and various types of chronic nephritis

The concentration of urinary fibrin(ogen) degradation products (FDP) was determined by using enzyme immunoassay and radio immunoassay, and their urinary levels were compared with histologically classified types of glomerulonephritis. Urinary FDP levels were higher in the severe type of proliferative glomerulonephritis and at the active phase of systemic lupus erythematosus (SLE). They were also high in the membranous glomerulonephritis. Molecular weight of urinary FDP of a patient with severe proliferative glomerulonephritis was determined to be 150,000 and 68,000, respectively after gel filtration. Urinary FDP levels were higher in patients with glomerular fibrin deposit than in patients without fibrin deposit or normal volunteers. The amounts of excreted protein in urine was not related to the amounts of FDP. Decrease in the reciprocal of serum creatinine levels resulted in high urinary FDP levels, indicating that high urinary FDP levels may represent deterioration of renal function.

Effects of fibrinolytic treatment on rabbit Masugi nephritis

We investigated the effects of administration of urokinase (UK) and trans-4-aminomethylcyclohexane carboxylic acid (t-AMCHA) on the development of experimental rabbit Masugi nephritis. Treatment with 1000 U/kg of UK, 5000 U/kg of UK and 100 mg/kg of t-AMCHA twice a day intravenously was initiated on the 7th and continued for 7 consecutive days. Concomitantly with the nephrotoxin injection, 5000 U/kg of UK was also given twice a day intravenously for 14 days. The administration of 5000 U/kg of UK twice a day for 7 days and 14 days suppressed the increases in BUN values and the decreases in urinary fibrinolytic activity. Fibrin-fibrinogen degradation products (FDP) were detected more frequently in the urine of rabbits given UK than in the control. Immunofluorescence microscopy showed a decrease in intra- and extra-glomerular fibrin deposition, and a decrease in fibrin or fibrinoid deposits in Bowman's space by 5000 U/kg of UK was demonstrated electron microscopically. Light microscopy revealed that the accumulation of fibrin in glomeruli, crescent formation, and progressive glomerular disorganization by 5000 U/kg of UK were prevented. On the other hand, treatment with t-AMCHA enhanced the increase in BUN values and there was a decrease in urinary fibrinolytic activity. Dense fibrin deposits in the glomeruli, were observed immunopathologically by treatment with t-AMCHA and histopathologic changes were found to be even more severe.

Determination of urinary fibrin/fibrinogen degradation products by radioimmunoassay

Glomerular fibrin/fibrinogen related material is often found in the early stage of especially proliferative types of glomerulonephritis and during rejection of renal grafts after transplantation. The presence and concentration of urinary fibrin/fibrinogen degradation products (FDP) have been found to be correlated to the extent of glomerular fibrin deposits. Most methods for FDP determination hitherto available are not sensitive enough to detect such small amounts of the fibrin/fibrinogen related material in the urine as are found in early glomerulonephritis. A radioimmunoassay for determining urinary FDP is described, in which the high molecular weight degradation products (HMWDP) are first converted into end degradation products (D and E) by addition of plasminogen and streptokinase to the urine sample. In the test an antiserum against purified D-products is used, which avoids the influence of varying binding properties and therefore makes the method more specific.

The role of coagulation and fibrinolysis in the development of rabbit Masugi nephritis

The role of coagulation and fibrinolysis in the pathogenesis of rabbit Masugi nephritis was studied. Fibrinolytic activity of urine decreased rapidly to the minimum values at the peak of the disease. Histologic observations showed a severe proliferative glomerulonephritis. Immunofluorescent studies revealed localization of rabbit gamma globulin along the glomerular basement membrane in a typical linear pattern. Fibrin was positive in glomeruli not only within fibrinoid deposits, but also often diffusely in the places where no obvious fibrin was detected in histologic sections. Bright strands of fibrin was present between the cells forming a cresent. Electron microscopy indicated accumulation of fibrinoid materials beneath the endothelium. The basement membrane was damaged by the deposition of fibrinoid and followed by massive escape of intracapillary contents into the Bowman's space. Abundant fibrin and fibrinoid were seen in newly formed "monocytic-epithelial" crescents. Todd's fibrinolysis autography revealed diminished fibrinolytic activity in the severely affected glomeruli. Treatment with heparin prevented crescent formation and glomerular disorganization, while treatment with t-AMCHA increased fibrin and fibrinoid deposition and aggravated the glomerular injuries. It was concluded that the coagulation-fibrinolysis system could play an important role in the course of rabbit Masugi nephritis.

The determination of fibrinolytic degradation products in concentrated urine after renal transplantation

Fibrin/fibrinogen degradation products (FDP) were determined in concentrated as well as unconcentrated urine in 29 patients undergoing renal transplantation. When determined in unconcentrated urine, FDP was found for 3-4 weeks after an uneventful transplantation, compared with 12 weeks when determined in concentrated urine. After acute rejection episodes FDP was found in unconcentrated urine, but remained in the concentrated urine for 8 weeks longer when concentrated urine was used for determination. In early chronic rejection and glomerulonephritis, FDP appeared as a sign of glomerular lesion in concentrated urine before it was found in unconcentrated urine. It was concljded that the presence of FDP in concentrated urine is a diagnostic tool of value particular in detecting early glomerular lesions caused by chronic rejection or glomerulonephritis.