Developmental research on the application of a microbial lectin CLA for the analysis of human-specific erythrocyte surface antigen.

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Possibility of practical use of CLA, a chitooligosaccharide-binding lectin from a fungus Conidiobolus lamprauges, was investigated. CLA binded to human erythrocytes highly specifically. It agglutinated human erythrocytes nonspecifically for blood groups at a concentration of 25 <micro> g protein/ml, agglutinated the erythrocytes of chimpanzee, gibbons, and tufted capuchin at an order of 1,000 <micro> g/ml, but agglutinated none of the erythrocytes of 47 species of other mammals, birds, reptiles, amphibia, and fishes. Animal species-specificity of CLA was too strict to apply CLA for the comparative studies on animals in taxonomy, evolutionology, and mass genetics, but suitable for human-animal blood diagnosis in police science. CLA detected human blood stains as old as 10 years and as little as 2.5 <micro> l. Differing from known anti-blood group antibodies, CLA was not inhibited by saliva and semen. This property gave an great advantage to CLA when it was used as the reagent for the mass diagnosis of occult blood in the early checkup of cancer on digestive organs. Generally CLA did not bind to human hemopoietic cells. Only exception was HEL, human erythroleukemia, cells. Tetradecanoyl phorbor acetate treatment of HEL cells resulted in the loss of CLA-bindability. CLA will be applicable for the clinical diagnosis of inherent and acquired blood diseases and the studies on the action of differentiation-inhibitory and stimulatory substances. CLA receptor on human erythrocytes was not glycolipid but glycoprotein, and in glycoprotein, not glycophorin and spectrin but Band 3 glycoprotein. Chemical and enzymological studies showed that the CLA required-for binding to the receptor the presence of L-fucosyl residue and a special structure in more than 5 sugar residues on nonreducing terminal of lactosaminoglycan chain of Band 3.