Carcinoembryonic antigen: characterization of binding with insoluble lectins

Membrane glycoproteins shed in defence of the cells of the gastrointestinal tract

The cells lining the gastrointestinal tract are exposed to various potentially harmful agents, including plant lectins and microorganisms. It is proposed that glycoproteins within the mucus layer of the gut protect against these agents. A hypothesis is presented that membrane glycoproteins are shed and, within the mucus close to the cell surface, block the binding of lectins or attachment of microorganisms to membrane receptors. A model is presented that demonstrates that such blocking can be achieved by soluble glycoproteins. The implications of this hypothesis in health and disease are discussed.