The correlation of antibodies to nuclear ribonucleoprotein (RNP) and nuclear acidic protein (Sm) with nephritis in patients with systemic lupus erythematosus (SLE).

The role of antibodies to Sm and RNP in renal diseases in SLE was investigated using counter immunoelectrophoresis (CIE). Antibody to RNP was found in about 50% of lupus patients irrespective of the degree of renal involvement as evaluated clinically, histologically and immunopathologically. Antibody to Sm was found more frequently in lupus patients with renal lesions than in those without renal disease. Antibody to RNP was demonstrated in 8 of 10 (80%) and antibody to Sm in 4 of 10 (40%) specimens obtained by elution of autopsied kidneys. These results suggest that antibodies to RNP and Sm are also of importance in the pathogenesis of lupus nephritis in addition to the already recognized role of antibody to ds-DNA.