Membranous Nephropathy: A Radioimmunologic Search for Anti-Renal Tubular Epithelial Antibodies and Circulating Immune Complexes

Abstract

In an effort to elucidate immunopathogenic mechanisms of membranous nephropathy (MN), freshly collected sera from patients with biopsy proven MN were assayed for circulating immune complexes (ICs) by the Raji cell method and for anti-renal tubular epithelial (RTE) antibodies by a newly established radioimmunoassay (RIA) and by indirect immunofluorescence. 6 of 26 MN patients tested by the Raji cell assay had detectable circulating ICs. However, 5 of these 6 patients had other medical conditions which might also explain the IC reactivity. 29 MN patients and 11 patients with other glomerular diseases had no demonstrable circulating anti-RTE antibodies. This study suggests that if RTE antigens possess a nephritogenic potential for man it is probably only rarely expressed. The inconstant detection of circulating immune complexes in idiopathic MN raises speculation as to their immunopathogenic significance.