Gold-induced immune complex nephritis in seronegative rheumatoid arthritis.

Proteinuria, with or without the nephrotic syndrome, developed in 8 patients with seronegative rheumatoid arthritis after the institution of gold therapy. Light microscope examination of renal biopsies showed normal findings in 7, and a focal increase in the mesangial matrix of one glomerulus in the eighth. In all patients immunofluorescence showed deposits of IgG and C3 along the glomerular basement membrane, indicative of immune complex nephritis. The renal biopsies of 5 patients were studied with the electron microscope and subepithelial deposits were detected in all. The Rose-Waaler test for the detection of IgM-rheumatoid factor (IgM-RF) was repeatedly negative in all patients. These results suggest that the development of gold nephropathy may be related to an absence of IgM-RF in serum.