Effect of cytokines on the proliferation and differentiation of acute promyelocytic leukemia cells: possible relationship to the development of "retinoic acid syndrome".

The effect of cytokines on the proliferation and differentiation of leukemia cells from 5 patients with acute promyelocytic leukemia (APL) was examined. Interleukin-1 beta (IL-1), interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) augmented uptake of 3H-thymidine into the DNA of APL cells in a dose-dependent manner in all cases. This stimulatory effect was pronounced in some, but not all, cells treated with all-trans retinoic acid (ATRA). However, nitroblue tetrazolium-reducing activity was induced in a concentration-dependent manner by ATRA in all cases. The cytokines greatly enhanced NBT reduction of APL cells treated with ATRA, and a mixture of cytokines was more effective than a single cytokine. Although GM-CSF, IL-3 and IL-1 significantly modulated the ATRA-induced morphological changes, they did not induce CD14 expression, a typical marker of monocytic differentiation. In the presence of ATRA, GM-CSF potentiated production and secretion of tumor necrosis factor-alpha (TNF) in response to lipopolysaccharide, as well as interferon-gamma which is a potent inducer of monocytic differentiation in APL cells. On the other hand, production of TNF in ATRA-treated cells was not affected by G-CSF which significantly enhanced granulocytic differentiation. The effect of cytokines on APL cell differentiation should be considered in ATRA treatment for APL patients. Potentiation of cytokine production in APL cells associated with myelomonocytic differentiation is noteworthy in the pathogenesis of "retinoic acid syndrome".