Pseudospecific magnetic affinity beads for immunoglobulin-g depletion from human serum

Magnetic poly(ethylene glycol dimethacrylate-N-methacryloyl-(L)-histidine methyl ester) [m-poly(EGDMA-MAH)] beads were prepared by suspension polymerization for the affinity depletion of immunoglobulin-G (IgG) from human serum in a batch system. Elemental analysis of the magnetic beads for nitrogen was estimated as 70 mu mol MAH/g polymer. IgG adsorption onto the m-poly(EGDMA) was negligible. Higher adsorption value (LIP to 46.8 mg/g) was obtained in which the m-poly(EGDMA-MAH) beads were used. IgG adsorption capacity of the magnetic beads increased with an increase in the concentration of IgG. The maximum IgG adsorption was observed at pH 6.5 for MOPS buffer. IgG molecules could be repeatedly adsorbed and eluted with these adsorbents, without noticeable loss in their IgG adsorption capacity. Adsorption capacity decreased for both increasing salt concentration and temperature. In this study, we show that m-poly(EGDMA-MAH) beads (wherein IgG molecules bind directly with the matrix) can be used directly for affinity depletion without further modification. Higher adsorption value was obtained frorn human serum (up to 85.7 mg/g). The elution results demonstrated that the adsorption of IgG to the adsorbent was reversible. The depletion efficiencies for IgG were above 85% for all studied concentrations. Eluted portion was analyzed for testing the IgG removal efficiency by two dimensional gel electrophoresis. Eluted proteins include mainly IgG, and a small number of nonalbumin proteins such as apolipoprotein A1, serotransferrin, haptoglobulin, and alpha 1-antitrypsin. IgA was not identified in eluted fraction. (c) 2007 Wiley Periodicals.