Delayed removal of renal-bound antigen in decomplemented rabbits with acute serum sickness.

We have examined the effects of complement depletion, brought about by cobra venom factor (CVF), on the clearance of radiolabelled BSA from the kidney in acute serum sickness in rabbits. The decomplemented group showed a significant decrease in the rate of clearance of renal-bound antigen with a mean half-clearance time of 19.5 days (range 9.3--60) vs 11.3 (range 8.7--15) for the control group. C3 was rapidly cleared from the glomerulus (as assessed by immunofluorescence) when further deposition was prevented by treatment with CVF. Glomerular immune complexes apparently activated the alternative pathway in vitro. These findings suggest that in immune complex nephritis, the clearance of deposited complexes from the kidney is complement-dependent.