| Abstract: | Substances with blood-group ABH(0) specificity are not confined to human red blood cells. Rather, such substances are ubiquitous antigenic surface structures which Nature has preserved throughout the phylogenetic development from microbes to man. — It could be shown experimentally that so-called “pre-existing natural” antibodies can result from inapparent immunization by these widely distributed antigens. — The blood-group specific structures of bacteria are chemically closely related to the determinant structures of the human blood-group ABH(0) glycoproteins. The situation is more complicated for the blood-group active substances from higher plants; these give extraordinary immunochemical reactions and two of their blood-group specific monosaccharides precipitate antibodies. — Recently the nature of the M and N blood-group antigens of erythrocyte surfaces has been elucidated. They are the main antigens of the second of at least 14 human blood-group systems. These substances, which are glycoproteins, are also excellent myxovirus receptors and inhibitors. The NN antigen is the first reported physically homogeneous, chemically defined and highly blood-group active cell surface structure of human origin. As surface structures, blood-group active substances appear to be frequently endowed with receptor properties in addition to those for blood-group antibodies. |
