Polyhydroxyethylmethacrylate-based magnetic DNA-affinity beads for anti-DNA antibody removal from systemic lupus erythematosus patient plasma

The aim of this study is to prepare magnetic poly(2-hydroxyethylmethacrylat e) (mPHEMA) beads and to investigate their utility for the removal of anti- DNA antibodies from systemic lupus erythematosus (SLE) patient plasma. mPHE MA beads, in the size range of 80-120 mum, were produced by a modified susp ension technique. Then, DNA was coupled onto mPHEMA beads by carbodiimide a ctivation. The amount off ligand coupled was changed by changing the initia l concentrations of carbodiimide and DNA. Human immunoglobulin G (HIgG) and anti-DNA antibody adsorption from aqueous solutions and human plasma were examined in a batch system. mPHEMA beads were characterized by swelling tes ts, electron spin resonance (ESR) and scanning electron microscopy. Importa nt results obtained in this study are as follows: the swelling ratio of mPH EMA beads was 34%. The presence of magnetite particles in the polymeric str ucture was confirmed by ESR. The mPHEMA beads have a spherical shape and po rous structure. Maximum DNA coupling of carbodiimide activated mPHEMA beads was 4.4 mg/g. Maximum HIgG adsorption from an aqueous solution was 47.5 mg /g. Anti-DNA antibody adsorption from SLE plasma was observed as 87.6 mg/g. Non-specific HIgG adsorption was 0.1 mg/g. More than 90% of the adsorbed H IgG molecules and anti-DNA antibodies were desorbed succesfully by using Na SCN solution. It was possible to reuse these DNA-affinity beads without sig nificant losses in the antibody adsorption capacities. (C) 2001 Elsevier Sc ience B.V. All rights reserved.