Purification of immunoglobulins from serum using thiophilic cellulose beads

This study evaluates the chromatographic performance of a support obtained by the reaction of mercaptoethanol with cellulose beads activated with divinyl sulfone. Cellulose beads 500-800 microns (μm) in diameter and with a solids content of 3.5% were selected for this study. A two-step sequence of permeation and reaction was used to install thiophilic sites throughout the cross section of the bead. The distribution of thiophilic sites was visualized by immobilizing fluorescent antibodies. Human and porcine serum proteins were separated on the thiophilic support at different linear velocities. Thiophilic cellulose beads were observed to bind human and porcine immunoglobulins (IgG) selectively from serum. Overall total protein recoveries in the range of 85%-99% were obtained with human serum, porcine serum and cell supernatant. Human IgG yields of 75% and 50% were obtained at linear velocities of 1 cm/min and 3 cm/min, respectively. Thiophilic cellulose beads were observed to bind monoclonal antibodies from cell culture supernatant but yields in the range of 40-50% were obtained. Purity of the products, obtained from a single chromatographic step, as judged by electrophoretic analysis was estimated to be greater than 80%.