Comparison of antigens and antisera in crossed immunoelectrophoresis by dual dilution

The localization of individual precipitates in the crossed immunoelectrophoresis (CIE) pattern is an important feature for their identification, but in a given system this pattern may vary markedly when different antigen preparations or antisera are used. Two different antigen preparations or antisera may be compared by mixing them in various proportions in a set of four CIE plates. The amounts of the preparations to be compared are selected to obtain a gradual change in position of individual precipitates if differences are encountered. Similarities between antigen or antibody preparations are recorded when the positions of precipitates remain unchanged. The technique is particularly valuable for comparing complex patterns with a large number of precipitate lines.