Plasma inhibitor of glomerular fibrinolysis in the hemolytic-uremic syndrome.

To detect an inhibitor of glomerular fibrinolysis, dilutions of human plasma were incubated on microscope slides with two frozen sections of normal human kidney. The slides were studied by the fibrin slide technique. The lysis inhibitory titer was defined as the highest dilution completely inhibiting glomerular fibrinolysis. Of 27 children without renal disease, none had a lysis inhibitory titer greater than 1:2. Defining an elevated lysis inhibitory titer as 1:8 or greater, we found an elevated lysis inhibitory titer in plasma from all 17 children with hemolytic-uremic syndrome. No correlation was found between the lysis inhibitory titer and the hematocrit, white blood cell or platelet counts, serum creatinine level, or levels of the antiplasmins alpha 1-antitrypsin, alpha 2-macroglobulin, C1-esterase inhibitor, or alpha 2-antiplasmin. The inhibitor was found to have a molecular weight of less than 12,000. A close correlation was discovered between the duration of lysis inhibitory titer elevation and the clinical course; removal of the inhibitor from the plasma by peritoneal dialysis was associated with improvement in renal function. Results suggest that the inhibitor may play an important role in the pathogenesis and persistence of glomerular fibrin deposition.