The adsorption of human IgG onto GMA (a semirigid methacrylate-based chromatography matrix) and His-GMA adsorbents was studied by chromatography and batch equilibrium binding analysis. IgG molecules adsorbed onto GMA gel by nonspecific hydrophobic interactions and the specificities were similar for both adsorbents. Adsorption data were analyzed using three isotherm models, namely the Langmuir, Freundlich and Langmuir-Freundlich models, and the adsorption parameters were computed. The experimental isotherms were best described by a combined Langmuir-Freundlich model, which indicated the presence of unequal binding sites on both adsorbents and/or positive cooperativity in the binding of the IgG molecules.

The affinity filtration technique using histidine as a pseudobiospecific ligand immobilized on poly(ethylene vinyl alcohol) hollow fiber membranes (His-PEVA) was used to remove autoantibodies from serum of patients with autoimmune disease. The effects of buffering solution conditions on the efficiency of autoantibodies removal was studied. The removal of anti-dsDNA, anti-SS-A/Ro, anti-Sm, anti-Sm/RNP and anti-cardiolipin autoantibodies present in the serum was investigated, comparing the efficiency between Hepes and Tris-HCl buffers. The results showed the potential of the membrane to remove all the autoantibodies studied. Anti SS-A/Ro was removed more efficiently in Tris-HCl buffer system rather than with the Hepes buffer.