title: Permissive role of interleukin 3 (IL-3) in proliferation and differentiation of multipotential hemopoietic progenitors in culture.
abstract: We studied the effects 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. The types of colonies were similar to those supported by pokeweed-mitogen spleen cell conditioned medium (PWM-SCM), except that IL-3 supported eosinophil and neutrophil expression better. Delayed addition of IL-3 to cultures 7 days after cell plating decreased the number of colonies to one-half the number in cultures with IL-3 added on day 0. It did not alter the proliferative and differentiation characteristics of late emerging multipotential blast cell colonies. These observations suggest that IL-3 does not trigger hemopoietic progenitors into active cell proliferation but is necessary for their continued proliferation. This permissive role of IL-3 is consistent with a stochastic model of stem cell proliferation which features random entry into cell cycle. IL-3 also supported the growth of multilineage colonies from single cells isolated from blast cell colonies by micromanipulation. This result shows that IL-3 acts directly on multipotential progenitors. Analysis of colonies derived from paired progenitors revealed disparate lineage expression and was in accordance with the stochastic model of stem cell differentiation.
mesh_terms: D000818:Animals; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D003470:Culture Media; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D007377:Interleukin-3; D008222:Lymphokines / Q000494:pharmacology*; D051379:Mice; D011043:Pokeweed Mitogens / Q000494:pharmacology; D013154:Spleen / Q000166:cytology
chemical_list: D003470:Culture Media; D007377:Interleukin-3; D008222:Lymphokines; D011043:Pokeweed Mitogens