Differential toxicity on normal and transformed Cells in vitro and inhibition of tumour development in vivo by concanavalin A

THE carbohydrate binding protein concanavalin A (Con A)^1-3 can agglutinate cells transformed by a variety of carcinogenic agents, but it only agglutinates normal cells after they have been treated with trypsin⁴. This agglutination was reversed by competition with α-methyl-D- glucopyranoside (α-MG). These results indicated that transformed cells contain exposed binding sites that interact with Con A, whereas most such sites on normal cells are in a cryptic form^4,5. These experiments were undertaken to determine whether treatment with Con A can result in cell toxicity; and if so, whether the difference in structure of the surface membrane between normal and transformed cells can result in a differential toxic effect, and can be used to inhibit tumour development in vivo.