Acid-phosphatase reaction in acute lymphoblastic leukaemia.

The diagnostic value of the acid-phosphatase reaction was assessed double-blind in 148 cases of acute lymphoblastic leukaemia (A.L.L.) classified by surface-membrane markers and entered into the M.R.C. U.K. A.L.L. trials. 90% of cases of T-A.L.L. showed a positive reaction in the majority of blast cells, while only 2% of common-A.L.L. and 10% of null-A.L.L. were positive. This cytochemical reaction distinguished the more aggressive form of A.L.L. any may aid the choice of therapy.