Oxidative modification of human β₂-GPI. Structural modifications in human β₂-GPI were demonstrated by 2-DE and IB with a polyclonal goat serum specific to the human β₂-GPI. Molecular weights are shown on the left (kDa). Native β₂-GPI contained a train spot representing the 7 isoforms with pIs ranging from 5.0 to 7.0 and with molecular weights ranging from 75 to 70 kDa (A). Human β₂-GPI, oxidized either after treatment with H₂O₂ (B) or spontaneously in the culture medium (C) gave a main train spot, fragments, and aggregates. In the H₂O₂-β₂-GPI preparation, additional fragments at 32.6 kDa appeared. The addition of a protease inhibitor cocktail to the DC culture medium left the 2-DE pattern unchanged (D).