Decreased adenosine deaminase activity in peripheral lymphocytes from tumor patients with metastasis.

We determined the levels of adenosine deaminase (ADA) activity in peripheral lymphocytes of 22 tumor patients: 54% had metastasis; 59% were undergoing chemotherapy at the time of the study. The mean ADA value of all patients was significantly lower than that of 15 healthy subjects of a similar age. When the patients were allocated by treatment and metastasis, the decrease of ADA activity appeared to be associated to the presence of metastasis.