Immune responses to small nuclear ribonucleoproteins: antigen-dependent distinct B cell epitope spreading patterns in mice immunized with recombinant polypeptides of small nuclear ribonucleoproteins.

Abstract

Complex patterns of autoantibody reactivities with the small nuclear ribonucleoproteins (snRNPs) are observed in systemic lupus erythematosus. To investigate the role of individual snRNP components in the initiation and diversification of anti-snRNP Ab responses, we immunized A/J mice with recombinant Smith D (SmD), Smith B (SmB), and A ribonucleoprotein (A-RNP) with alum as adjuvant. Sera at different time points after initial immunizations were analyzed by Western blot and immunoprecipitation assays. In SmD-immunized mice, specific Abs to A-RNP and SmB were generated by 2 mo postimmunization, in addition to the detection of cross-reactive Abs between the immunogen and other snRNPs. Whereas Abs reactive with the immunogen decreased by 5 mo, Abs capable of immunoprecipitating A-RNP and SmB increased. In SmB-immunized mice, specific Abs to A-RNP were readily detectable, in addition to cross-reactive Abs. In contrast, A-RNP-immunized mice had only cross-reactive Abs to SmB without detectable Abs to SmD. However, in these mice, specific Abs to the 70-kDa protein were generated. Abs, which precipitated the native snRNP particle, were generated in all three groups of the immunized mice. Our results show that different initiating Ags from the same multiprotein antigenic complex induce distinct patterns of epitope spreading to proteins within that complex. These data have significant implications for the mechanisms of autoantibody diversification in systemic lupus erythematosus.

• Authors: Umesh S Deshmukh, Carol C Kannapell, Shu Man Fu
• Journal: Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 168 Issue 10 Pg. 5326-32 (May 15 2002) ISSN: 0022-1767 [Print] United States
• PMID: 11994491 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Autoantibodies
• Autoantigens
• Epitopes, B-Lymphocyte
• Immune Sera
• Peptides
• RNA, Small Cytoplasmic
• Recombinant Proteins
• Ribonucleoproteins
• Ribonucleoproteins, Small Nuclear
• SS-A antigen
• Snrpb protein, mouse
• Ssa2 protein, mouse
• snRNP Core Proteins

Topics

• Animals
• Autoantibodies (biosynthesis, blood)
• Autoantigens (administration & dosage, genetics, immunology, metabolism)
• Cross Reactions
• Epitopes, B-Lymphocyte (immunology, metabolism)
• Female
• Immune Sera (blood)
• Immunization
• Injections, Subcutaneous
• Mice
• Mice, Inbred A
• Peptides (administration & dosage, immunology, metabolism)
• Precipitin Tests
• Protein Biosynthesis (immunology)
• RNA, Small Cytoplasmic
• Recombinant Proteins (administration & dosage, genetics, immunology, metabolism)
• Ribonucleoproteins (administration & dosage, genetics, immunology, metabolism)
• Ribonucleoproteins, Small Nuclear (administration & dosage, genetics, immunology, metabolism)
• Transcription, Genetic (immunology)
• Tumor Cells, Cultured
• snRNP Core Proteins