Glomerular fibrinolytic activity during nephrotoxic nephritis

The glomerular fibrinolytic activity (GFA) was measured during the development of glomerulonephritis induced by the intravenous injection of horse or rabbit antiglomerular basement membrane antibodies in rats either untreated or preimmunized with horse or rabbit Ig. A variety of nephritides was produced ranging from proteinuria with no or mild changes in glomerular architecture to severe diffuse proliferative glomerulonephritis with close to 100% crescent formation. GFA was measured on preparations of isolated glomeruli using a radioassay based on lysis of 125I fibrin adsorbed on a solid phase. In some experiments a fibrin plaque technique was also used. Both methods clearly demonstrated a marked increase in GFA with a good correlation between the two sets of results when the glomerular architecture is preserved. The increase in GFA is related both to the severity of the nephritis estimated by the percentage of glomeruli showing crescent formation and to the extent of the fibrin deposits. The results therefore indicate that the persistence of fibrin in the glomeruli and particularly in crescents is not due to a loss of GFA.