Interleukin 5 and its receptor.
IL-5 is a cytokine mainly produced by T lymphocytes, especially when they are sensitized with microorganisms, which induce eosinophils and Ly-1 positive B lineage cells, both of which are probably engaged in the primary protection against micro-organisms. These possibilities are discussed by analyzing IL-5 transgenic mice. We also discuss the possibility of using these mice as animal models for the diseases which may be caused by increased levels of eosinophils. Although IL-5 is not produced by bone marrow stromal cells, it is involved in the early development of eosinophils and Ly-1 positive B-lineage cells that can differentiate into macrophages. The clue to the role of IL-5 may exist in the constitution of IL-5 receptor. The IL-5 receptor consists of alpha and beta chains. The alpha chain is a 60 kDa glycosylated protein which binds IL-5, by itself, with low affinity. On the other hand, the 130 kDa beta chain does not bind IL-5 by itself, but forms high affinity IL-5 receptors together with the alpha chain. Surprisingly, this beta chain is probably shared with the GM-CSF receptor and is very homologous to the IL-3 receptor. It seems that the beta chain is expressed in the very early stage of hematopoiesis. The alpha chain may be directly related to the cell lineage commitment.
Takatsu
K
K
Department of Biology, Kumamoto University Medical School, Japan.
Tominaga
A
A
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000502:physiology; D002454:Cell Differentiation; D003001:Cloning, Molecular; D004804:Eosinophils / Q000166:cytology / Q000502:physiology; D006801:Humans; D015848:Interleukin-5 / Q000502:physiology*; D046911:Macromolecular Substances; D051379:Mice; D008822:Mice, Transgenic; D011971:Receptors, Immunologic / Q000502:physiology*; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5; D015398:Signal Transduction
D015848:Interleukin-5; D046911:Macromolecular Substances; D011971:Receptors, Immunologic; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5