Immunological classification of acute lymphoblastic leukaemias: evaluation of its clinical significance in a hundred patients.

The use of T and B lymphocyte markers and of different antisera raised against malignant B cells and fetal thymocytes allowed the classification of 100 patients with acute lymphoblastic leukemia (ALL) into three groups. (I) Patients with non-T non-B ALL whose cells were devoid of conventional B and T markers but characterized by a leukaemia associated antigen (69 cases). (2) Patients with T-derived ALL (28 cases). (3) Patients with ALL of B cell origin (three cases). The search for haematological and clinical correlations showed that those patients with T-derived ALL tended to have a higher leucocyte count (P=0.05) and acid phosphatase positivity of blast cells (P= 0.01), a higher incidence of tumour presentation (P=0.05) and a thymic mass. Survival curves for the two main groups of patients are similar at 36 months but meningeal relapses were more frequent in patients with T-derived ALL (P=0.02).