Serum adenosine deaminase activity in brain tumours.

Adenosine deaminase (ADA) activity in serum was estimated in 86 patients with intracranial tumours and 40 healthy volunteers. Although high ADA concentrations in biological fluids and tumour tissues were observed in several neoplastic conditions, there was no significant difference in the ADA in sera of brain tumour patients when compared to the control values. Therefore, cell-mediated immunity probably does not play a significant role in brain tumours.