Estimation of the Homogeneity of Purified Ragweed Antigens¹

The antigenic homogeneity of three purified ragweed antigens has been studied by an antiglobulin coprecipitation technique using human antiserum. They were approximately 84, 67 and 64% homogeneous as determined by this procedure. Smaller amounts of other antigens were also present. Only one major precipitin band was found, and it was common to all three preparations. The utility and the limitations of the coprecipitation procedure were considered. The occurrence and significance of multiphasic binding curves in heterogeneous systems were discussed with the aid of a model consisting of a mixture of purified antigens and homologous antibodies.