5'-nucleotidase activity in myeloma cells.

Plasma cells were studied cytochemically for 5'-nucleotidase (5'-N) activity in bone marrow smears from 11 patients with multiple myeloma and 12 cases with no haematological disorders but with adequate numbers of plasma cells. The activity of 5'-N could be demonstrated in about 90% of myelomatous plasma cells. The non-myelomatous plasma cells of control smears were negative for 5'-N activity. The activity of 5'-N did not seem to be affected by storage of unfixed smears for up to 5 months at room temperature.