Non-proteic immunogenic impurity in proteins purified by preparative electrophoresis on Pevikon

Purified IgA proteins, obtained by zonal electrophoresis on blocks of Pevikon, contained an uncharged, non-proteic, water-soluble macromolecular impurity. The contaminant, which precipitates in half-saturated ammonium sulfate, could be an unknown derivative of polyvinyl alcohol. It was discovered because it induced the synthesis of specific precipitating antibodies in a rabbit used for antibody production against the electrophoresed protein, generating spurious precipitin reactions during its immunochemical analysis. Thorough washing of the Pevikon will substantially reduce the amount of impurity and the danger of obtaining precipitating antibodies against it after injection into animals.