Immuno-chemical studies on blood groups; the preparation of blood group A and B substances and an inactive substance from individual horse stomachs and of blood group B substance from human saliva.

Blood group substances have been isolated from the saliva of human beings of blood group B and from the linings of individual horse stomachs. The properties of the human B substances are similar to those of hog and human blood group substances previously isolated. The horse substances showed lower hexosamine and reducing sugar and higher total and non-hexosamine nitrogen than do the materials from the other species. Materials isolated from individual horse stomachs possess either A or B activity or both. Certain stomachs yielded products of identical analytical composition but with neither blood group A, B, or O activity as measured by their ability to inhibit isoagglutination. Fucose has been identified as a constituent of the horse blood group substances.