SLA/LP/tRNP((Ser)Sec) antigen in autoimmune hepatitis: identification of the native protein in human hepatic cell extract.

Abstract

A diagnostic subgroup of AIH type 1 is characterized by specific serum antibodies against soluble liver protein. The respective autoantigen was named SLA/LP/tRNP((Ser)Sec), after three homologous recombinant polypeptides were isolated from expression gene libraries. We analyzed human cultured liver cells for the human homologue of recombinant SLA/LP/tRNP((Ser)Sec) by antigen purification. In addition, a monoclonal antibody was generated against recombinant SLA-p35, a truncated recombinant SLA-reactive polypeptide. With a positive patient serum, immune affinity chromatography was performed on the 52 kD-SLA main antigenic determinant pre-enriched by ion exchange chromatography. By mass spectrometry, the 52 kD-SLA/LP/tRNP ((Ser)Sec) autoantigen was unambiguously identified in the purification product. The identity of the recombinant SLA-p35 and its human homologue was further confirmed by a specific signal of the anti SLA-p35 monoclonal antibody with purified human SLA/LP/tRNP((Ser)Sec). The 48 kD-SLA species frequently comigrating in SLA-immunoblotting however was not identified by either approach. We conclude that the native counterpart of recombinant tRNP((Ser)(Sec)) indeed is detectable with a molecular weight of 52 kD in soluble liver extract of human cells as the major antigenic component of SLA/LP/tRNP((Ser)Sec).

• Authors: Martin Volkmann, Daniel Luithle, Hanswalter Zentgraf, Martina Schnölzer, Sabine Fiedler, Hans Heid, Andrea Schulze-Bergkamen, Christian P Strassburg, Sven G Gehrke, Michael P Manns
• Journal: Journal of autoimmunity (J Autoimmun) Vol. 34 Issue 1 Pg. 59-65 (Feb 2010) ISSN: 1095-9157 [Electronic] England
• PMID: 19683415 (Publication Type: Journal Article)
• Copyright: Copyright 2009 Elsevier Ltd. All rights reserved.

Chemical References

• Antibodies, Monoclonal
• Autoantigens
• Cell Extracts
• Peptide Fragments
• RNA, Transfer, Amino Acyl
• Recombinant Proteins
• selenocysteinyl-tRNA

Topics

• Amino Acid Sequence
• Antibodies, Monoclonal (metabolism)
• Autoantigens (blood, genetics, immunology, metabolism)
• Cell Extracts
• Cell Line, Tumor
• Chromatography, Affinity
• Cloning, Molecular
• Hepatitis, Autoimmune (blood, diagnosis, immunology, metabolism)
• Hepatocytes (immunology, metabolism, pathology)
• Humans
• Mass Spectrometry
• Molecular Sequence Data
• Peptide Fragments (blood, genetics, immunology, metabolism)
• RNA, Transfer, Amino Acyl (blood, genetics, immunology, metabolism)
• Recombinant Proteins (blood, genetics, immunology, metabolism)