[Cytochemical detection of lymphocyte 5'-nucleotidase in chronic lymphatic leukemia]

5'-Nucleotidase is a degrading purine ectoenzyme acting at alkaline pH. It is located in both B and T lymphocytes and its study is of interest in chronic lymphoproliferative diseases. The present work compiles the cytochemical study of lymphocyte 5'-nucleotidase in a control group consisting of 277 haematologically normal subjects and a series of 77 chronic lymphocytic leukaemia (CLL) patients; phenotypic studies had been carried out in 40 of these last. The results were expressed as percentage of 5'-nucleotidase positive lymphocytes, and the value (means +/- SD) for the control group was 25 +/- 7, that of the CLL group being 10.7 +/- 18.12. Increased lymphocyte 5'-nucleotidase was present in a minority of the cases (13%), but the significance of this finding is unknown and unrelated to any clinical or cytomorphological data. Although lacking any statistical value, those B-CLL lymphocytes expressing surface IgM and IgD (thus being more mature cells) showed higher 5'-nucleotidase values than those cells expressing only IgM. This finding suggests that a given lymphocytic population would be more immature the lower 5'-nucleotidase value it may express. The incorporation of 5'-nucleotidase determination into the cytochemical study of CLL is encouraged as it is frequently decreased in this disease; at the same time, the enzyme may provide some information on the maturity of the leukaemic population involved.