Detection and quantification of human anti-Sm antibodies using synthetic peptide and recombinant SmB antigens.
Anti-Sm-positive sera from patients with systemic lupus erythematosus (SLE) recognize a major epitope located within the carboxyl-terminal 27 amino acids of a recombinant SmB fusion protein. To determine whether a synthetic peptide corresponding to this region could be used as an antigen to detect anti-Sm antibodies, sera were typed as anti-Sm positive or anti-Sm negative by counterimmunoelectrophoresis (CIE). Twenty-three SLE sera that were anti-Sm positive by CIE, 22 that were anti-Sm negative by CIE, and 42 sera from patients with other autoimmune diseases were tested for anti-Sm antibodies by enzyme-linked immunosorbent assay (ELISA), using either the synthetic peptide (C27) or a recombinant SmB (rSmB) fusion protein as the antigen. More than 90% of the sera that were anti-Sm positive by CIE were also positive by both the C27 and rSmB ELISAs, and an additional 2 SLE sera originally typed as anti-Sm negative were found to be positive (1 by the C27 ELISA, 1 by the rSmB ELISA), due to the greater sensitivity of the ELISAs. In the rSmB ELISA, anti-Sm antibodies were not detected in any of the sera from patients with other autoimmune diseases, whereas 3 patients with anti-U1 RNP antibodies (1 each with polymyositis, scleroderma, and mixed connective tissue disease) had a positive result in the C27 ELISA. These results indicate that both the C27 synthetic peptide and rSmB are excellent antigens for use in ELISAs to quantify anti-Sm antibodies.
Hines
J J
JJ
Hospital for Special Surgery, Cornell University Medical Center, New York, New York 10021.
Danho
W
W
Elkon
K B
KB
D000906:Antibodies / Q000032:analysis*; D001324:Autoantigens / Q000276:immunology*; D001327:Autoimmune Diseases / Q000097:blood / Q000276:immunology; D003378:Counterimmunoelectrophoresis; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000276:immunology; D011994:Recombinant Proteins; D012261:Ribonucleoproteins / Q000276:immunology; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins
D000906:Antibodies; D001324:Autoantigens; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; C526407:SNRPB protein, human; D055517:snRNP Core Proteins