Adenosine deaminase and purine nucleoside phosphorylase activities in peripheral blood cells of patients with neoplastic diseases. I. Bronchogenic carcinoma.

By means of sensitive and specific radiochromatographic methods the activities of adenosine deaminase and purine nucleoside phosphorylase in peripheral blood cells of patients with bronchogenic carcinoma were estimated. It has been shown that purine nucleoside phosphorylase activity was two- to three-fold higher in lymphocytes of patients with epidermoid as well as other types of bronchogenic carcinoma in comparison with a group of healthy individuals. Adenosine deaminase activity in lymphocytes was elevated only in the group of patient with nonepidermoid carcinoma. The authors suggest that especially the estimation of purine phosphorylase activity in lymphocytes would be a useful laboratory test in the study of immune responsiveness of patients with bronchogenic carcinoma.

Inhibition of bovine heart adenosine deaminase activity by some pyrimidine analogues.

Some pyrimidine analogues--especially 6-azauridine and 5-azacytidine at a final concentration of 1 mmol dm-3--significantly depressed adenosine deaminase activity isolated and purified from bovine heart. Both the above mentioned azapyrimidine nucleosides were effective competitive inhibitors of this enzyme. The inhibitory effect of some clinically used pyrimidine analogues may be of importance for explanation of their mechanisms of action on the cell metabolism.