Clonal growth of haemopoietic progenitor cells from myelodysplastic marrow in response to recombinant haemopoietins.

The growth factor requirements of granulocyte-macrophage (GM) and erythroid marrow progenitor cells from 12 myelodysplastic (MDS) patients have been analysed. GM progenitors from two of six patients who grew normal numbers of colonies in response to conditioned medium + erythropoietin (5637CM + Epo) showed defective responses to either GMCSF and/or IL-3. Of all the recombinant factors tested (IL-3, IL-1, GCSF, GMCSF, MCSF), GMCSF was the strongest stimulator of myeloid clonal growth, inducing normal numbers of GM colonies from marrow of six patients (two of whom were neutropenic). Erythroid colonies were low in 5637CM + Epo-supplemented cultures of marrow from all but one patient and remained poor in the presence of any of the haemopoietins. tested. Supraoptimal doses (for normal marrow) of these haemopoietins improved colony growth in only one patient (GM colonies in response to IL-3). Combinations of factors were also largely ineffective at raising myeloid or erythroid colony numbers. These data indicate that the defective response of MDS progenitor cells to growth factors is not amenable to experimental manipulation of recombinant factor levels or combinations. Clonal assays might suggest a role for GMCSF therapy in a subpopulation of neutropenic MDS patients but their potential now needs to be evaluated in association with clinical trials.