The nature of ABH-blood-group antigens in saliva was investigated. Human saliva was examined serologically for ABH-blood-group activity in its native form and after various treatments. The activity of the native form persisted in the delipidated samples, but was entirely lost after alkaline degradation. The lipid portion of saliva was completely inactive in the ABH hemagglutination inhibition system. The same results were obtained when purified glycolipid fraction of saliva was used instead of whole lipid extract. Neither alkaline treatment nor excessive amounts of salivary lipids effected antigenic activity of A-active glycosphingolipids of hog gastric inucosa admixed to saliva samples before alkaline degradation and/or in presence of large amounts of salivary lipids.The isolated glycolipid fractions contained at least eight glycolipids, each of which was composed of glucose, glyceryl ethers and fatty acids and differed from others with respect to number of glucose residues.Sphingosine and sugar residues involved in formation of ABH antigenic determinants were not detected.These findings together with data 011 stomach secretion [1,2] led US to the conclusion that ABHblood-group antigens of saliva are exclusively of glycoprotein nature.The search for the understanding of blood group activity and the nature of tissue antigens has revealed the importance of specific carbohydrate chains. However, the question of what is the nature of bloodgroup-active antigens from secretions and from tissue cells has not been answered.From the work of Schiff, Freudenberg, Torpes, Goebel, Meyer and their many coworkers [3 -51 much useful chemical evidence has been gained about materials with blood group activity and their complexity.The study of Friedenreich and Hartmann [6] and Hartmann [7] revealed a dual nature of blood-groupactive antigens; a water-soluble form found only in body fluids and secretions and an alcohol-soluble form present on tissue cells and erythrocytes.Discovery of blood-group-active antigens of glycosphingolipids and glycoprotein origin from the same source [8 -191 led to the proposal of their coexistence in the tissues and to the assumption [20] that secretions represent also a mixture of blood-group-active glycosphingolipids and glycoproteins. Also, the evidence was presented on the glycoprotein nature of ABH antigens of erythrocytes [21,22] which were known for long time to contain antigens of the glycosphingolipid character. These data created a chaotic picture of the distribution of blood-group-active glycosphingolipids and glycoproteins.The results presented here together with our earlier studies on glycolipids of gastric secretion [I, 2,23,24] strongly suggest an orderly distribution ofglycoprotein and glycolipid type of ABH antigens, which is in strict agreement with the early observations of Friedenreich and Hartmann [6,7], that alcohol-soluble substances are exclusively present in tissue, whereas water-soluble glycoprotein antigens represent secretory products.
MATERIALS AND METHODS
MaterialsSaliva...