Gel filtration in Sephadex G200 for the control of preparations of human immunoglobulin.

Gel filtration in Sephadex G200 has been used in the quality control of normal and specific immunoglobulins at the Blood Products Laboratory, Elstree, for more than eleven years. Eluting from a 140 cm column, polymerised and aggregated protein is excluded by the gel, followed in order of elution by fractions containing the IgG dimer and the monomer. After these, smaller protein impurities such as albumin are eluted and then fragments from the proteolytic breakdown of IgG. On a single chromatogram, possibly five distinct peaks may be recorded and their components quantified. Gel filtration in Sephadex G200 provides an alternative to sedimentary boundary ultracentrifugation, by which fragmentation of IgG can be more readily observed. In addition, the fraction containing the polydisperse aggregates excluded by the gel provides an index of adverse treatment of immunoglobulin during preparation and storage.