Interleukin 5

Interleukin 5
250px Crystal structure of human IL-5
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 1HUL, 3QT2, 3VA2
Identifiers
Symbols	IL5 ; EDF; IL-5; TRF
External IDs	OMIM: 147850 MGI: 96557 HomoloGene: 679 ChEMBL: 1169600 GeneCards: IL5 Gene
Gene ontology Molecular function • cytokine activity • interleukin-5 receptor binding • protein binding • growth factor activity Cellular component • extracellular region • extracellular space Biological process • inflammatory response • immune response • cytokine-mediated signaling pathway • positive regulation of B cell proliferation • positive regulation of eosinophil differentiation • positive regulation of JAK-STAT cascade • positive regulation of peptidyl-tyrosine phosphorylation • positive regulation of immunoglobulin secretion • positive regulation of sequence-specific DNA binding transcription factor activity • positive regulation of podosome assembly Sources: Amigo / QuickGO
RNA expression pattern
File:PBB GE IL5 207952 at tn.png
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	3567	16191
Ensembl	ENSG00000113525	ENSMUSG00000036117
UniProt	P05113	P04401
RefSeq (mRNA)	NM_000879	NM_010558
RefSeq (protein)	NP_000870	NP_034688
Location (UCSC)	Chr 5: 132.54 – 132.56 Mb	Chr 11: 53.72 – 53.73 Mb
PubMed search	[1]	[2]

Interleukin 5 or IL-5 is an interleukin produced by T helper-2 cells and mast cells.

Function

Through binding to the IL-5 receptor, IL-5 stimulates B cell growth and increases immunoglobulin secretion. It is also a key mediator in eosinophil activation.

Structure

IL-5 is a 115-amino acid (in human, 133 in the mouse) -long TH2 cytokine that is part of the hematopoietic family. Unlike other members of this cytokine family (namely IL-3 and GM-CSF), this glycoprotein in its active form is a homodimer.

Tissue expression

The IL-5 gene is located on chromosome 11 in the mouse, and chromosome 5 in humans, in close proximity to the genes encoding IL-3, IL-4, and granulocyte-macrophage colony-stimulating factor (GM-CSF), which are often co-expressed in TH2 cells. Interleukin-5 is also expressed by eosinophils and has been observed in the mast cells of asthmatic airways by immunohistochemistry. IL-5 expression is regulated by several transcription factors including GATA3.

Clinical significance

Interleukin-5 has long been associated with the cause of several allergic diseases including allergic rhinitis and asthma, wherein a large increase in the number of circulating, airway tissue, and induced sputum eosinophils have been observed. Given the high concordance of eosinophils and, in particular, allergic asthma pathology, it has been widely speculated that eosinophils have an important role in the pathology of this disease.

Effect of IL-5 on Eosinophils

Eosinophils are terminally differentiated granulocytes found in most mammals. The principal role of these cells, in a healthy host, is the elimination of antibody bound parasites through the release of cytotoxic granule proteins. Given that eosinophils are the primary IL-5Rα-expressing cells, it is not surprising that this cell type responds to IL-5. In fact, IL-5 was originally discovered as an eosinophil colony-stimulating factor, is a major regulator of eosinophil accumulation in tissues, and can modulate eosinophil behavior at every stage from maturation to survival. Mepolizumab is a monoclonal antibody against IL-5 which can reduce excessive eosinophilia.

In Hodgkin lymphoma, for instance, the typically-observed eosinophilia is thought to be attributable to an increased production of IL-5.

Interactions

Interleukin 5 has been shown to interact with Interleukin 5 receptor alpha subunit.

Receptors

The IL-5 receptor is composed of an α and a βc chain. The α subunit is specific for the IL-5 molecule, whereas the βc subunit also recognised by interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Glycosylation of the Asn196 residue of the Rα subunit appears to be essential for binding of IL-5.