Demonstration of a receptor for activated C3 in the human renal glomerulus
More than 90% of immunologically mediated renal disease results from immune complex (I C) deposition in glomerular basement membrane, yet the cause of this selective deposition is unknown. The authors report the discovery of a tissue bound receptor for activated C3 (C3b) located almost exclusively within the glomerulus of the human kidney. This receptor was demonstrated by incubating frozen sections of human kidney with the I C IgMEAC (SRBC(E) coated with 19S anti SRBC antibody (A) and complement (C)). E or EA are not bound. EAC made with human, guinea pig (GP) or mouse C were bound. The glomerular C3 receptor is specific for C3b because EA coated with purified GP or human C1, C14, C142, or C 1423d are not bound. Demonstration of the glomerular C3 receptor required I C coated heavily with C3b. I C formed by activation of C3 via the alternative pathway (fluorescein labeled bacteria coated with C3b) were also bound. The glomerular C3 receptor was found in all human autopsies including kidney from a one day old child and 6 of 10 biopsies thus far examined. A likely, though not yet proved, location for the glomerular C3 receptor is the surface of the mesangial cell. The glomerular C3 receptor may explain selective deposition of I C and provide a new understanding of the pathogenesis of I C renal disease.
Gelfand, MC; Edelson, RK; Frank, MM; Green, I
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