Tubulointerstitial immune complex nephritis in rats immunized with Tamm-Horsfall protein

Rats immunized with Tamm-Horsfall protein (TH) developed autoantibodies to TH and tubulointerstitial nephritis with granular deposits of IgG, C3, and TH at the base of tubular cells of the thick ascending limb of Henle's loop and selective infiltration of leukocytes around this distal nephron segment. Selective IgG deposition at the base of cells in the tubular segment containing TH and the direct relationships of the amount of immune deposits and the severity of histologic lesions to serum levels of anti-TH antibodies suggest a pathogenetic role for the autoantibodies to TH. The immune deposits in this model of tubulointerstitial nephritis appear to be the consequence of in situ formation of immune complexes. This mechanism involves the diffusion of circulating antibodies to TH across tubular basement membranes and their combination with TH molecules associated with tubular cell surface membranes.