title: Interleukin 3 (IL 3) regulates the in vitro proliferation of both blood monocytes and peritoneal exudate macrophages: synergism between a macrophage lineage-specific colony-stimulating factor (CSF-1) and IL 3.
abstract: The effect of interleukin 3 (IL 3) on regulation of macrophage proliferation was examined. Although IL 3 alone stimulates the colony formation in bone marrow cells, it fails to stimulate the colony formation by both peritoneal exudate macrophages (PEM) and blood monocytes. However, IL 3 greatly enhances the proliferative capacity of both PEM and monocytes in responding to suboptimal concentrations of CSF-1. At supraoptimal concentrations of CSF-1, IL 3 did not increase the number of colonies, but greatly increased colony size. Kinetic studies showed that IL 3 enhances CSF-1-induced macrophage proliferation by shortening the cell doubling time. Monocytes were more sensitive to the action of IL 3 and possessed higher proliferative potential than PEM. Binding studies with radioactive labeled CSF-1 (125I-CSF-1) showed that IL 3 treatment induced an increased expression of CSF-1 receptor activity by PEM which appears to be a result of increased number of available receptor sites. The effect of IL 3 on the expression of receptor activity is both dose- and time-dependent. IL 3 also augments the rate of receptor-mediated CSF-1 endocytosis by PEM which appears to be a direct result of increased expression of CSF-1 binding sites. These results demonstrate that, in addition to stimulating the growth and differentiation of several blood cell lineages by hemopoietic stem cells, IL 3 also possesses the ability to modulate CSF-1 receptors, thereby affecting proliferation of more mature blood monocytes and tissue-derived macrophages.
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000276:immunology; D002454:Cell Differentiation; D003115:Colony-Stimulating Factors / Q000378:metabolism / Q000502:physiology*; D004357:Drug Synergism; D005260:Female; D007377:Interleukin-3; D008222:Lymphokines / Q000378:metabolism / Q000502:physiology*; D008262:Macrophage Activation; D008264:Macrophages / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D009000:Monocytes / Q000276:immunology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D016184:Receptors, Colony-Stimulating Factor
chemical_list: D003115:Colony-Stimulating Factors; D007377:Interleukin-3; D008222:Lymphokines; D011956:Receptors, Cell Surface; D016184:Receptors, Colony-Stimulating Factor