EFFECTS OF MYELOID CELL-GROWTH FACTORS ON ALKALINE-PHOSPHATASE, MYELOPEROXIDASE, DEFENSIN AND GRANULOCYTE-COLONY-STIMULATING FACTOR-RECEPTOR MESSENGER-RNA EXPRESSION IN HEMATOPOIETIC-CELLS OF NORMAL INDIVIDUALS AND MYELOID DISORDERS

The mRNA expressions of alkaline phosphatase (ALP), myeloperoxidase (M PO), defensin and G-CSF receptor (G-CSFR)in bone marrow cells of norma l individuals and myeloid disorders, with or without in vitro stimulat ion by myeloid cell growth factors, i.e. G-CSF, GM-CSF and IL-3, were examined as markers for myeloid cell differentiation in both mononucle ar cell (MNC) and polymorphonuclear cell (PMN) fractions, Without any stimulation, ALP mRNA was expressed only in PMNs, G-CSFR mRNA in PMNs were expressed stronger than in MNCs; both MPO and defensin mRNA were expressed to the same degree in both fractions, With stimulation, the ALP mRNA expression in both fractions was strongly enhanced by G-CSF, but the expression was inhibited by GM-CSF and/or IL-3. MPO mRNA expre ssion was stimulated by G-CSF and/or GM-CSF in MNCs. G-CSFR mRNA expre ssion was enhanced by G-CSF in both fractions. Defensin mRNA expressio n was inhibited by G-CSF. In cases of myelodysplastic syndrome and chr onic myelogenous leukaemia which display a suppressed maturation of my eloid cells, our results demonstrated an almost normal response to the se growth factors. Our results suggest that studies on these myeloid m arker mRNA expressions would provide more knowledge about the differen tiation state and cytokine reactivity of myeloid cells in normal indiv iduals as well as various disorders.