THE EFFECT OF INTERLEUKIN-4 WITH OR WITHOUT MAST-CELL GROWTH-FACTOR ON PERIPHERAL-BLOOD GRANULOCYTE-MACROPHAGE COLONY-FORMING CELLS IN HEALTHY CONTROLS AND IN MYELOPROLIFERATIVE DISORDERS

The effect of interleukin-4 (IL-4) on peripheral blood (PB) granulocyt e-macrophage (GM) progenitors was investigated in the presence and abs ence of other hematopoietic growth factors, especially the mast cell g rowth factor (MGF), in eight healthy controls and in 26 patients with myeloproliferative disorders (MPDs) using a clonogenic cell culture as say. In the controls IL-4 was effective alone, stimulating myeloid col ony growth in 50%, while MGF had no effect as a single factor. When ei ther IL-4 or MGF was added to the combination of IL-3, GM-CSF, G-CSF, and IL-6, a statistically significant increase in the colony number wa s observed. The most potent colony formation took place when all these GFs were combined. In the combinations, the effect of IL-4 was additi ve, while MGF worked synergistically. In the MPDs, IL-4 had no effect at all on the GM progenitors in the whole group of MPDs or on the diff erent subgroups.