Anti-5S RNA/protein (RNP) antibody levels correlate with disease activity in a patient with systemic lupus erythematosus (SLE) nephritis.

SUMMARY A patienl with systemic lupus erythematiosus (SLE) and nephritis without antibodies to dsDNA but with antibodies lo a 5S RNA/protcin (RNP) complex is presented. Combined RNA precipitation and Western blotting experiments strongly suggested that these newly Identified autoantibodics recognized a distinct epitope on the 1.5 ribosomal protein of the L5/5S RNP complex first described by steitz et al. [1]. Quantification of the anti-5S RNI* antibody levels was done by hybridizing Northern blots of immunoprecititated RNA from serial serum samples with a 32p-labelled oligoprobc specific for the 5S ribosomal RNA. These studies revealed a strong association between unti-5S RNP autoanlibody litre and severity of SLE nephritis over a 3-ycar prospective study. Our results indicate 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 therapy.