Diverse antibody recognition patterns of the multiple Sm-D antigen polypeptides.
Anti-Sm antibodies are intrinsically associated with systemic lupus erythematosus. The major targets are the so-called B and D polypeptides. The number of Sm targets increased upon the report that SDS-PAGE conditions could be manipulated to display not one, but three Sm-D polypeptides. To characterize the relative reactivities of Sm-D1, Sm-D2, and Sm-D3, both human and murine autoantibodies were screened. These sera displayed two distinct patterns of reactivity. The Sm-D1/D3 pattern was at least four times more common than Sm-D1/D2/D3 recognition. The predominant immunoreactive protein was Sm-D1. We screened over 40 monoclonal antibodies that were derived from MRL mice and were selected as anti-Sm positive. Of these, 27 reacted with at least one Sm-D polypeptide by protein blot, but in contrast to the MRL sera, none of these antibodies reacted with Sm-D2. Rather, there were two recognition patterns of approximately equal abundance, against Sm-D1/D3 or Sm-D1 alone. Last, we explored the immune response to isolated Sm-D (containing all three D antigens) from rabbit thymus. The autoantibody produced reacted only with Sm-D2. There is accumulating evidence that the anti-Sm response is at least partially antigen-driven. The details of the intragroup relationships within the Sm-D family of proteins provide further insight into the Sm autoimmune response.
Hoch
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La Jolla Institute for Experimental Medicine, La Jolla, California, 92037, USA. shoch@agi.org
Eisenberg
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Sharp
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D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D019463:Mice, Inbred MRL lpr; D010455:Peptides / Q000276:immunology*; D011817:Rabbits; D017411:Ribonucleoproteins, Small Nuclear / Q000276:immunology*; D055517:snRNP Core Proteins
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D001324:Autoantigens; D010455:Peptides; D017411:Ribonucleoproteins, Small Nuclear; C526411:SNRPD2 protein, human; C090865:Sm protein D2; C090866:Sm protein D3; D055517:snRNP Core Proteins