International standards for IgG and IgM anti-β2glycoprotein antibody measurement

R. Willis, C. Grossi, M. Orietta Borghi, G. Martos-Sevilla, I. Zegers, J. Sheldon, P. L. Meroni

Research output: Contribution to journalArticlepeer-review


International standards for anti-beta2 glycoprotein I (anti-β2GPI) testing are needed. We evaluated the suitability of polyclonal/monoclonal candidate reference materials (RM) for the assay. IgG/IgM anti-β2GPI were affinity-purified (AP) from high-positive antiphospholipid syndrome sera and IgG from HCAL clone supernatant. Igs were tested for purity by SDS-PAGE, pooled, concentrated, sterile-filtered and the protein concentration determined. One unit was defined as the binding activity of 1-μg/ml of AP anti-β2GPI Ig. IgG/IgM RM were each assigned a unit value using the respective AP material as a calibrator. Polyclonal/monoclonal RM and 30 samples were evaluated for linearity, unit equivalency and commutability. Polyclonal AP material was assigned a value of 100 U IgG and 15-U IgM anti-β2GPI, respectively. IgG-RM had a value of 270 IgG and the IgM-RM of 220.3 IgM anti-β2GPI U. The linearity (R2) of each RM curve for the various assays ranged from 0.96 to 0.99. Commutability samples fit very well within 95% prediction intervals and had excellent correlation when comparing assays. IgG and IgM polyclonal and IgG monoclonal RM displayed excellent linearity and commutability, being good candidates for better standardization of anti-β2GPI immunoassays.

Original languageEnglish
Pages (from-to)1317-1319
Number of pages3
Issue number12
Publication statusPublished - Oct 8 2014


  • Anti-β2glycoprotein I antibodies
  • reference materials
  • standardization

ASJC Scopus subject areas

  • Rheumatology
  • Medicine(all)


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