Adenosine deaminase activity in acute lymphoblastic leukaemia: cytochemical, immunological and clinical correlations.

Adenosine deaminase (ADA) activity has been assessed in lymphoid cells of 23 patients with acute lymphoblastic leukaemia (ALL) in order to attempt a further characterization of ALL cells in addition to the well known cytochemical and immunological T and B lymphoid cell markers. ADA activity did not show any correlation with the immunological characterization of the patients investigated; in fact a wide range of ADA activity was observed with levels ranging from 0 to 32 U in T-ALL patients and nearly similar values (from 1.8 to 36 U) in the group of non T--non B ALL cases. Normal values ranged from 2 to 5 U (mean 2.9 U; s.d. +/- 0.8). Some cytochemical patterns (acid phosphatase and PAS) appeared well correlated with T markers of lymphoid cells, whereas they showed no significant relationship with ADA activity.