Active in situ immune complex glomerulonephritis using the hapten-carrier system: role of epitope density in cationic antigens.

The role of epitope density in cationic antigen was investigated in an active model of in situ immune complex glomerulonephritis (ICGN) using the hapten-carrier system. Trinitrophenol (TNP) was conjugated with variable density to cationic human immunoglobulin (C-HIgG) to yield TNP6.2-C-HIgG (low-valency antigen) and TNP31.3-C-HIgG (high-valency antigen). In rats preimmunized with TNP17.3-bovine serum albumin (BSA), endocapillary proliferative GN with proteinuria developed in rats receiving high-valency antigen. In contrast, no significant abnormalities in renal histology or urinalysis were observed when a low-valency antigen was injected. These results indicate that glomerular injury produced by hapten-specific immune reaction is affected by the number of haptenic groups conjugated to the carrier molecule (epitope density) in active in situ ICGN.