Optimization of Unnickedβ2-Glycoprotein I and High Avidity Anti-β2-Glycoprotein I Antibodies Isolation
Patient biological material for isolation ofβ2-glycoprotein I (β2GPI) and high avidity IgG anti-β2-glycoprotein I antibodies (HAv anti-β2GPI) dictates its full utilization. The aim of our study was to evaluate/improve procedures for isolation of unnickedβ2GPI and HAv aβ2GPI to gain unmodified proteins in higher yields/purity. Isolation ofβ2GPI from plasma was a stepwise procedure combining nonspecific and specific methods. For isolation of polyclonal HAv aβ2GPI affinity chromatographies with immobilized protein G and humanβ2GPI were used. The unknown protein found during isolation was identified by liquid chromatography electrospray ionization mass spectrometry and the nonredundant National Center for Biotechnology Information database. The average mass of the isolated unnicked purifiedβ2GPI increased from 6.56 mg to 9.94 mg. In the optimized isolation procedure the high molecular weight protein (proteoglycan 4) was successfully separated fromβ2GPI in the 1st peaks with size exclusion chromatography. The average efficiency of the isolation procedure for polyclonal HAv anti-β2GPI from different matrixes was 13.8%, as determined by ourin-houseanti-β2GPI ELISA. We modified thein-houseisolation and purification procedures of unnickedβ2GPI and HAv anti-β2GPI, improving the purity of antigen and antibodies as well as increasing the number of tests routinely performed with thein-houseELISA by ~50%.