Nephrotic syndrome, monoclonal gammopathy and auto-immune hyperlipidaemia.

Hyperlipidaemia, glomerulonephritis and IgG λ monoclonal gammopathy were found to be associated in two patients (Ler. and Lac.). A severe atherosclerosis was also present in the former patient. After a purification–activation procedure active IgG λ was obtained from the serum chylomicra and from the ammonium sulphate-precipitated serum gamma-globulins. In passive haemagglutination tests, including inhibition tests, the IgG λ Ler. reacted specifically with the protein moiety of human low density lipoproteins (LDL) and the IgG λ Lac. reacted with human, rat and rabbit very low density lipoproteins (VLDL) as well as with human serum albumin (HSA). These IgG λ behaved like autoantibodies though no activity was found in whole serum, in which they are probably blocked by the corresponding antigens. They are very similar, although not identical, to the autoantibodies found in auto-immune hyperlipidaemia (AIH) and it is proposed that in these patients the hyperlipidaemia is a variety of AIH. Finally it is suggested that the hyperlipidaemia associated with glomerulonephritis chiefly in the nephrotic syndrome may sometimes be AIH. If this is the case the renal lesions and the hyperlipidaemia may be different expressions of an immune complex disease which may also lead to other tissue lesions such as atherosclerosis.