Decrease in 5'-nucleotidase activity in malignant transformed and normal stimulated cells.

Analysis of six different cell types of normal and transformed fibroblasts grown in vitro and of four different cell types of normal and leukemic lymphocytes grown in vivo have shown a marked decrease of 3- to 30-fold in the specific activity of 5'-nucleotidase in the malignant cells as compared to their normal parental cells. The results have also indicated that a serum stimulation of untransformed or normal fibroblasts and a stimulation of normal lymphocytes by concanavalin A resulted in a significant decrease in the specific activity of 5'-nucleotidase of the stimulated cultures as compared to the resting cells. In both the malignant cells and the stimulated normal cells, the decrease in 5'-nucleotidase activity was not accompanied by a similar decrease in the specific activity of acid phosphatase, indicating a specific enzyme alteration in the surface membranes of the transformed and the normal stimulated cells.