The binding of lupus-derived autoantibodies to the C-terminal peptide (83-119) of the major SmD1 autoantigen can be mediated by double-stranded DNA and nucleosomes.
OBJECTIVE
To evaluate the binding of lupus-derived autoantibodies, double-stranded DNA and nucleosomes to the positively charged C-terminal SmD1(residues 83-119) peptide and the full-length SmD protein.


METHODS
The binding of lupus-derived monoclonal antibodies, sera from patients with systemic lupus erythematosus, rheumatoid arthritis and systemic sclerosis, dsDNA and nucleosomes to the SmD1(83-119) peptide or the full-length SmD protein was determined using different ELISA methods.


RESULTS
Monoclonal anti-dsDNA antibodies and the serum of patients with systemic lupus erythematosus that are positive for anti-dsDNA antibodies react with the SmD1(83-119) peptide in ELISA. However, DNaseI treatment of the blocking reagents leads to a decreased reactivity. Purified dsDNA and nucleosomes bind to the SmD1 peptide but not to the full-length SmD protein.


CONCLUSIONS
The SmD1(83-119) peptide is able to bind dsDNA and nucleosomes, and dsDNA or nucleosomes in applied reagents lead to an apparent reactivity of anti-dsDNA, anti-histone or nucleosome-specific antibodies with the SmD1(83-119) peptide in ELISA.
Nephrology Research Laboratory, Nijmegen Centre for Molecular Life Sciences, Division of Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
J W
JW
Dieker
C C
CC
Van Bavel
G
G
Riemekasten
J H
JH
Berden
J
J
van der Vlag
D000818:Animals; D000974:Antibodies, Antinuclear / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000378:metabolism; D000936:Antigen-Antibody Complex / Q000276:immunology; D001323:Autoantibodies / Q000378:metabolism*; D001324:Autoantigens / Q000378:metabolism*; D004247:DNA / Q000276:immunology / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D051379:Mice; D008814:Mice, Inbred NZB; D009707:Nucleosomes / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism*; D055517:snRNP Core Proteins
D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D001324:Autoantigens; D004268:DNA-Binding Proteins; D009707:Nucleosomes; D017411:Ribonucleoproteins, Small Nuclear; C526409:SNRPD1 protein, human; D055517:snRNP Core Proteins; D004247:DNA; D003850:Deoxyribonuclease I