Specific adsorption of the autoantibodies from rheumatoid arthritis patient plasma using histidine-containing affinity beads

Rheumatoid arthritis is characterized by chronic polyarthritis and destruction of multiple joints. In this study, poly(hydroxyethyl methacrylate-N-methacryloyl-(L-histidine)-methylester) (PHEMAH) beads were used in the removal of pathogenic antibodies from rheumatoid arthritis patient plasma in a packed bed column. PHEMAH beads, in the size range of 80-120 mum, were produced by suspension polymerization. The beads were contacted with blood in an in vitro system. Loss of blood cells and clotting times were followed. PHEMAH beads were characterized by scanning electron microscopy. We found that PHEMAH beads had a spherical shape and porous structure. Loss of cells in the blood contacting with PHEMAH beads was negligible. IgM-antibody adsorption capacity decreased significantly with the increase of the plasma flow-rate. With increasing IgM-antibody concentration, the amount of IgM-antibody adsorbed per unit mass increased and then reached saturation. Maximum IgM-antibody adsorption amount was 69.2 mg/g. IgM-antibody molecules could be repeatedly adsorbed and desorbed without noticeable loss in the IgM-antibody adsorption amount.