ANTI-5S RNA PROTEIN (RNP) ANTIBODY-LEVELS CORRELATE WITH DISEASE-ACTIVITY IN A PATIENT WITH SYSTEMIC LUPUS-ERYTHEMATOSUS (SLE) NEPHRITIS/

A patient with systemic lupus erythematosus (SLE) and nephritis withou t antibodies to dsDNA but with antibodies to a 5S RNA/protein (RNP) co mplex is presented. Combined RNA precipitation and Western blotting ex periments strongly suggested that these newly identified autoantibodie s recognized a distinct epitope on the L5 ribosomal protein of the L5/ 5S RNP complex first described by Steitz ct al. [1]. Quantification of the anti-5S RNP antibody levels was done by hybridizing Northern blot s of immunoprecipitated RNA from serial serum samples with a P-32-labe lled oligoprobe specific for the 5S ribosomal RNA. These studies revea led a strong association between anti-5S RNP autoantibody titre and se verity of SLE nephritis over a 3-year prospective study. Our results i ndicate that the L5/5S RNP can be a target of autoimmune response, and may serve, in some cases, as marker of SLE severity and response to t herapy.