[Selective staining of T-lymphoblastic leukemia cells by glycyl-prolyl-4-methoxy-beta-naphthylamiden-peptidase (DAP...

In search for new methods to maintain a selective and specific visualization of blast cells in cases of acute lymphoblastic leukemia the glycyl-prolyl-4-methoxy-beta-nephthylamide-peptidase reaction (DAP IV) was performed in cytochemical tests. Blood and marrow slides from 15 cases of acute lymphoblastic leukemia of childhood were stained. The results were compared with findings in Pappenheim and acid phosphatase stained slides. In addition slides from concentrated blood lymphocytes of 50 normal subjects served as control. The following results were achieved. 1. In normal blood only about 50% of T-lymphocytes reveal a positive DAP IV reaction. 2. Lymphocytes positive to DAP IV show a typical dot-like paranuclear pattern of activity for acid phosphatase. 3. Only 5 cases out of 15 acid phosphatase positive acute lymphoblastic leukemias presented a positive reaction for the DAP IV. DAP IV reaction is specially useful in visualization and quantification of blast cells in hypercellular marrow slides. In positive cases it further allows a reliable evaluation of the mark infiltration and duration of remission.