An assessment of the influence of antigen dose in two new models of chronic serum sickness glomerulonephritis in the rat.

Two new models of chronic serum sickness glomerulonephritis have been developed and characterized, using cationic and native bovine serum albumin (BSA). During this development, it has become apparent that there exists an optimum nephritogenic dose for native (anionic) BSA, above which the severity of glomerular changes diminishes; but for cationic BSA, higher doses consistently produce more severe lesions. This finding supports the theory that antigens of different charge are deposited in the glomerulus by different mechanisms. We have also found that cationic BSA circulates not in the blood plasma, but mainly bound to red cells. The two experimental models have proved to be more convenient and more consistent than those previously reported; the cationic BSA model also induces heavy proteinuria and the nephrotic syndrome. They will facilitate further studies of how antigen-antibody complexes are handled by the glomerulus in chronic immune complex disease.