Effect of dipyridamole, theophyllamine and verapamil on spontaneous in vitro proliferation of myelogenous leukaemia cells.

Dipyridamole strongly inhibited spontaneous in vitro proliferation of peripheral blood mononuclear cells from patients with acute myelogenous leukaemia (n = 9), chronic myelogenous leukaemia in first chronic phase (n = 4) and blast phase (n = 1). Theophyllamine and verapamil also inhibited proliferation of leukaemia cells from all patients except the CML patient in blast phase where only minimal inhibition was seen. Only dipyridamole caused strong inhibition in concentrations corresponding to the therapeutic serum level, and this inhibition was not influenced by the presence of high levels of interleukin 2.