抄録
We studied the effect of interleukin-3 (IL-3) on colony formation by hemopoietic progenitors in methylcellulose cultures of spleen cells from 5-fluorouracil (FU)-treated mice. Purified IL-3 supported the growth of various types of multilineage colonies including blast cell colonies. IL-3 supported the growth of multilineage colonies from single cells isolated from blast cell colonies by micromanipulation. This results shows that IL-3 acts directly on multipotential progenitors. Analysis of colonies derived from paired progenitors revealed disperate lineage expression and was in accordance with the stochastic model of stem cell differentiation.
Next, we examined the effect of purified IL-3 and erythropoietin on colony formation in serum-free cultures. In the presence of IL-3 alone, most of the multilineage (three or more lineages) colonies did not contain erythroid cells. However, in the presence of IL-3 and erythropoietin, most of the multilineage colonies contained various numbers of erythroid cells. Replating experiments suggest that IL-3 maintains the growth of the progenitor cells, which could differentiate into erythroid cells. Erythropoietin facilitated the terminal differentiation and amplification of erythroid cells, although it did not sustain the growth of multipotential stem cells. Single cell transfer experiments demonstrate that IL-3 supported the late stages of differentiation of neutrophils, macrophages, and mega karyocytes in the absence of lineage specific factors.
IL-3 plays a permissive role in proliferation and differentiation of multilineage hemopoietic progenitors in culture, and does not determine the differentiation pathway of cells.
