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Quantitative studies of the effects of defibrination (with ancrod) have been undertaken in two forms of allergic glomerular damage, nephrotoxic serum nephritis and acute serum sickness in rabbits. No differences in intrarenal fixation of nephrotoxic antibody, complement activation or host antibody response were detected between defibrinated and untreated rabbits with nephrotoxic serum nephritis. Defibrination prevented intraglomerular fibrin deposition in this disease; but some glomerular damage as shown by a rise in blood urea and endothelial proliferation still occurred in defibrinated animals. No differences in immune elimination of BSA, circulating immune complex formation or intrarenal localization of immune complexes were noted in defibrinated animals with acute serum sickness. No intraglomerular fibrin deposition was detected in treated or untreated animals in this disease model. It is concluded that the protective effects of ancrod are directly related to defibrination, and not to any other modification of allergic events.

The role of complement has been studied in the autologous phase of nephrotoxic nephritis (NTN) in rabbits. No reduction in glomerular fibrin deposition, crescent formation or protection from renal failure was observed in either the standard model of NTN when decomplementing doses of cobra venom factor (CVF) were given before the autologous phase or in a telescoped model when CVF was administered before the nephrotoxic antibody. In the latter situation glomerular fibrin deposition and crescent formation were found in the absence of detectable deposition of C3. However, substantial protection was observed when circulating polymorphonuclear leucocytes (PMN) were depleted by antipolymorph serum. These observations establish the existence of a system of allergic glomerular injury mediated by PMN but independent of C3. It is postulated that this system may account for the glomerular injury seen in patients with Goodpasture's syndrome in whom glomerular C3 deposition is not found.

The role of polymorphonuclear leucocytes (PMN) in the autologous phase of nephrotoxic nephritis (NTN) in the rabbit has been investigated. Depletion of circulating PMN by nitrogen mustard protected renal function and immunofluorescent examination showed reduction in glomerular fibrin deposition. Depletion of circulating PMN using a highly specific goat anti-PMN serum (APS) provided similar protection of renal function, highly significant reduction in proteinuria and histological and immunofluorescent examination showed reduced glomerular PMN infiltration, extracapillary cell proliferation and virtual absence of fibrin deposition. Although protection by nitrogen mustard may have been partly due to immunosuppression, no reduction in antibody response was detected in the APS-treated rabbits. The results implicate the polymorph as the principal injurious agent in this model of NTN, responsible directly or indirectly for both proteinuria and glomerular fibrin deposition.