Proliferation and maturation of human leukemic cells in liquid culture: activity of human placenta conditioned medium and retinoic acid.

Marrow or peripheral blood cells from 28 patients with acute myeloid leukemia (AML) or chronic myeloid leukemia in blastic crisis (CML-BC) were studied in both liquid and agar cultures. The proliferation and maturation of these cells were followed for 15-20 days in liquid culture with or without the addition of human placenta conditioned medium (HPCM) and/or retinoic acid (RA). In nine patients (group 1), cells underwent both proliferation and maturation, i.e., the percentage of peroxidase-positive cells (PO), phagocytic cells, and mature forms increased. For the remaining 19 patients (group 2), no proliferation was observed. However, 11 of these leukemic cell samples showed maturation (group 2A), while the eight others remained immature (group 2B). In agar culture, cell samples from group 1 showed cluster growth, group 2 no growth. Maturation without proliferation was observed for group-1 liquid cultures not containing HPCM and those containing HPCM and RA. The viability rapidly decreased in liquid cultures with only addition of RA. HPCM and RA showed no effect on group-2 cell cultures.