Bovine serum albumin (BSA) nephritis in rats. I. Experimental model.

Proliferative glomerulonephritis with proteinuria was induced in Wistar rats by bovine serum albumin (BSA). Rats were first immunized with 1 mg or 2.5 mg of BSA and complete Freund's adjuvant (CFA) and eight weeks later 1 mg of BSA were given intravenously six times a week for four weeks. Immunofluorescence revealed granular deposits of IgG, C3, and BSA in the mesangial area with or without deposition of the same components along the capillary wall. Evaluation of the circulating antibody disclosed an apparent correlation between the level of antibody and histological findings. Rats with an intermediate amount of antibody production developed mesangial widening with mesangial immune deposits and no proteinuria. Rats with a low response developed proliferative glomerulonephritis with immune deposits along the capillary wall as well as in the mesangial area and proteinuria.