title: Factors masking HMGB1 in human serum and plasma.
abstract: High mobility group box 1 protein (HMGB1) is a ubiquitously expressed architectural chromosomal protein. Recently, it has become obvious that HMGB1 can also act as a proinflammatory mediator when actively secreted during cell activation or passively released from necrotic cells. HMGB1 appears to play an important role in the pathogenesis of diseases, including sepsis and rheumatoid arthritis. However, easy, sensitive, and reliable detection systems are required to investigate the clinical significance of HMGB1 in clinical samples for diagnosis and prognosis of diseases. Here, we describe sensitive ELISAs for the detection of HMGB1 in cell culture medium and cell lysates. However, these assays failed to reliably quantitate HMGB1 in serum and plasma when compared with immunoblot analysis. We found that serum/plasma components bind to HMGB1 and interfere with its detection by ELISA systems. In most serum/plasma samples investigated, including those from healthy individuals, we detected IgG antibodies binding to HMGB1. The titers of these antibodies correlated with the capacity of sera to interfere with the detection of recombinant HMGB1 by ELISA. Furthermore, HMGB1 coimmunoprecipitated with several proteins including IgG1, as identified by mass spectrometry. These HMGB1 interacting proteins are currently characterized and may contribute to complex formation, masking, and possibly, modulation of cytokine activity of HMGB1.
authors.affiliation: IZKF Research Group 2, Nikolaus-Fiebiger-Center of Molecular Medicine, University of Erlangen-Nürnberg, and Department of Internal Medicine 3, University Hospital Erlangen, Germany.
authors.forename: Vilma
authors.initials: V
authors.lastname: Urbonaviciute
authors.forename: Barbara G
authors.initials: BG
authors.lastname: Fürnrohr
authors.forename: Christian
authors.initials: C
authors.lastname: Weber
authors.forename: Martin
authors.initials: M
authors.lastname: Haslbeck
authors.forename: Sabine
authors.initials: S
authors.lastname: Wilhelm
authors.forename: Martin
authors.initials: M
authors.lastname: Herrmann
authors.forename: Reinhard E
authors.initials: RE
authors.lastname: Voll
mesh_terms: D015415:Biomarkers / Q000097:blood*; D015153:Blotting, Western; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D024243:HMGB1 Protein / Q000097:blood* / Q000378:metabolism; D006801:Humans; D011485:Protein Binding; D011994:Recombinant Proteins / Q000097:blood
chemical_list: D015415:Biomarkers; D024243:HMGB1 Protein; D011994:Recombinant Proteins