Effects of dipyridamole and R-verapamil on in vitro proliferation of blast cells from patients with acute myelogenous leukaemia.

Cytokine-dependent AML cell proliferation was investigated in 16 patients. Dipyridamole and R-verapamil caused a dose-dependent inhibition of AML cell proliferation, and for both drugs the degree of inhibition was similar when testing various haematopoietic growth factors or growth factor combinations (IL3, G-CSF, GM-CSF, G-CSF + GM-CSF, TNF-alpha + GM-CSF). TNF-alpha alone increased AML cell proliferation for five patients, whereas four patients showed unaltered or decreased proliferation. Independent of this TNF-alpha effect, R-verapamil inhibited proliferation for all AML patients in the presence of TNF-alpha, whereas dipyridamole caused only a weak inhibition.