Solid Phase Immunoassay for the Detection of Anti-β₂ Glycoprotein I Antibodies

The discovery in the 1990s that the protein beta-2-glycoprotein I (β₂GPI) was an antigen of central importance in the antiphospholipid syndrome (APS) was soon followed by the development of ELISA assays capable of identifying anti-β₂GPI antibodies recognizing this antigen. The determination of these antibodies has continued to play a major role in the management of APS patients because of their extremely high specificity for diagnosing the disease, despite their relatively poor sensitivity compared to anticardiolipin antibodies. Additionally, there is abundant evidence of the pathogenic capacity of these antibodies. In this chapter we outline the procedure for producing essential assay components and for performing the anti-β₂GPI ELISA, which can be used to determine the presence of IgG, IgM and IgA anti-β₂GPI antibodies in human samples. We also provide general guidelines that will facilitate optimal performance of the anti-β₂GPI ELISA assay.