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A survey of the occurrence of lympho-agglutinins was carried out on seeds of 150 species of wild and cultivated plants. Potent agglutinins were detected in 17 extracts by employing lymphocytes of man, guinea pig, goat and sheep in the bioassay. Except for one species each of Mimosoideae, Euphorbiaceae and Clusiaceae, all the agglutinins were found in fabaceous seeds. Two of the agglutinins, namely, Parkia biglandulosa and Erythrina arborescens, were found to be monospecific for guinea pig and human lymphocytes, respectively, while the others agglutinated lymphocytes of 2-4 different species. The agglutination inhibition tests revealed the predominance of galactose (or its derivatives) binding lectins over those specific for glucose-mannose series.

Lympho-agglutinins have been detected and characterized in 31 plant species. Out of these, 14 agglutinated only the neuraminidase-treated cells. The lectin-rich genera included Crotalaria and Erythrina (Fabaceae), Amaranthus (Amaranthaceae), Artocarpus (Moraceae) and Clerodendron (Verbenaceae). The new lectins varied in their potency and biological action spectra. The 3 Artocarpus species were found to be exceptionally potent and specific for melibiose, an alpha-D-galactoside. Among the most effective sugar inhibitors for other lectins were N-acetyl-galactosamine, lactose, galactose and asialofetuin/fetuin.