Immunoadsorption of cholesterol on protein A oriented beads

Abstract

Anti-low density lipoprotein antibody (anti-LDL) molecules were attached covalently and oriented through Protein A onto poly(2-hydroxyethyl methacrylate-ethylene glycol dimethacrylate) [poly(HEMA-EGDMA)] beads in order to remove cholesterol specifically from hypercholesterolemic human plasma. Poly(HEMA-EGDMA) beads were produced by suspension polymerization. Blood compatibility tests were performed. All the clotting times were increased when compared with control plasma. Loss of platelets and leukocytes was very low. The maximum anti-LDL attachment was 11.6 mg · g-1 in the case of random immobilization and 28.3 mg · g-1 in the case of oriented immobilization. In the latter case, Protein A loading was 8.3 mg · g-1 at pH 7.5 (borate buffer, 0.15 M NaCl). There was low non-specific cholesterol adsorption onto the poly(HEMA-EGDMA) beads, about 0.83 mg · g-1. Random and oriented anti-LDL attached beads adsorbed 8.2 mg and 11.7 mg cholesterol per g of bead from hypercholesterolemic human plasma, respectively. Up to 96% of the adsorbed cholesterol was desorbed. The binding-elution cycle was repeated 6 times using the same beads. There was no significant loss of binding capacity.