5'-Nucleotidase in lymphocytes from various clinical disorders.

The enzyme 5'-nucleotidase (5'-N) was demonstrated cytochemically in blood cells using a modification of the Wachstein and Meisel technique [30]. In peripheral blood the activity was found to be localised mainly in the cell membrane of lymphocytes. A semiquantitative score of 5'-N positivity, was assessed in lymphocytes from eight normal donors and 60 patients with various types of leukaemia and lymphoma. The lymphocyte score of 5'-N was slightly reduced in CML and AML but markedly reduced in most lymphoproliferative states tested. The only supranormal activity was found in two of 18 cases of CLL.