Immunofluorescence characterization of light chains in human nephropathies.

Renal tissue from 185 patients with various nephropathies were studied by immunofluorescence, in order to look for the frequency and potential predominance of kappa or lambda light chain glomerular deposits. Four normal renal biopsies were used as controls. An overall study shows that light chains were present in glomeruli in 136 out of 185 cases; kappa light chain deposits were more frequent than lambda light chain deposits (73.5% and 64.3% respectively). An analytical study shows that this was not observed in all nephropathies studied. In mesangial IgA nephropathy, lambda light chain deposits were seen in 81% of cases (29 out of 37) and kappa light chain deposits were observed in 78% (30 out of 37 cases). In lupus nephritis, lambda light chain deposits were present in 13 out of 14 cases (92.8%) whereas kappa light chain deposits were demonstrated in 12 cases (85.7%). In other nephropathies such as membranous, endocapillary proliferative and amyloid nephritis, kappa was the predominant light chain observed in glomeruli or was present in the same number of cases as lambda light chain (mesangiocapillary glomerulonephritis). These findings show that in certain nephritides, for example IgA nephropathy and lupus nephritis, IgA and IgG deposits are mainly composed of lambda light chain in contrast with the normal kappa: lambda ratio in human serum of 2:1.