[Heterogeneity of the gastric intrinsic factor autoantibodies of types I and II]

Variable results were obtained in a study of the immunologic reaction of the intrinsic factor (IF)-autoantibodies (IFA) to the human, hog and rat IF antigens. Effectively, some IFA I were unable to block completely all the binding sites of B12 to IF. As to the IFA II, some did not show a total effectiveness in neutralizing the activity of IF in certain human gastric juices. In another study conducted on patients with pernicious anemia, the antibodies obtained from their sera reacted differently to the hog and rat IF; some reacted identically to homologous and heterologous IF others were less and even not effective on the heterologous IF. From these results it was suggested that, within the two main branches of IFA, there would be subdivided groups with selective effect on different antigenic sites of IF.