Role of the interleukin 5 receptor system in hematopoiesis: molecular basis for overlapping function of cytokines.
Interleukin 5 (IL-5) is a kind of peptide hormone released from T lymphocytes of mammals infected with microorganisms or parasites. It is an acidic glycoprotein with a molecular mass of 40 to 50 kDa that consists of a homodimer of polypeptides. It controls hematopoiesis so that it increases natural immunity. In the mouse, IL-5 acts on committed B cells to induce differentiation into Ig-producing cells and on common progenitors for CD5+ pre-B cells and CD5+ macrophages to support their survival. The antibodies secreted by CD5+ B cells seem to be responsible for the primary protection against the infection with microorganisms or parasites. It also supports the growth and/or differentiation of eosinophil precursor and mature eosinophils, which can be effective for the removal of parasites in combination with the antibodies against them. Murine IL-5 receptor (IL-5R) consists of two different polypeptide chains; alpha chain and beta chain. The IL-5R alpha chain is 60 kDa protein that binds IL-5 with low affinity. The IL-5R beta chain is a 130 kDa protein which does not bind IL-5 by itself but is necessary to form the high affinity IL-5R. The beta chain was identified by using one of the anti-IL-5R mAb and anti-IL-3R mAb as the IL-3R homologue. This beta chain is also used as the beta chain of GM-CSF receptor. This fact suggests that there is a common signaling mechanism among these cytokines and efficient cooperation among them. At the same time, these findings may explain the overlapping role of these cytokines in the development of granulocytes.
Department of Biology, Kumamoto University Medical School, Japan.
A
A
Tominaga
S
S
Takaki
Y
Y
Hitoshi
K
K
Takatsu
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D016175:B-Lymphocyte Subsets / Q000187:drug effects / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D016207:Cytokines / Q000502:physiology; D004804:Eosinophils / Q000187:drug effects; D006410:Hematopoiesis / Q000502:physiology*; D006801:Humans; D015848:Interleukin-5 / Q000737:chemistry / Q000494:pharmacology / Q000502:physiology*; D008213:Lymphocyte Activation; D051379:Mice; D008954:Models, Biological; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry; D018123:Receptors, Interleukin / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D053649:Receptors, Interleukin-5; D015398:Signal Transduction; D016176:T-Lymphocyte Subsets / Q000378:metabolism
D000911:Antibodies, Monoclonal; D016207:Cytokines; D015848:Interleukin-5; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5