Interleukin 5 (IL-5) is also known as B-cell growth factor II. IL-5 is pleiotropic cytokine that is primarily produced by TH2 cells and eosinophils. It plays important roles in promoting the differentiation of B-cells into immunoglobulin-secreting cells, stimulating IgA secretion, and activating eosinophils. IL-5 is involved in the pathology of allergic diseases and is a key target for drugs developed to treat severe asthma. Levels of IL-5 are typically low in the blood of healthy people, so measuring this cytokine in serum or plasma may require an ultra-sensitive assay. Ultra-sensitive versions of assays CANNOT be multiplexed.
Name: Ultra-sensitive Interleukin 5 (IL-5)
Category: Health & Inflammation
Type of test: Blood
Interleukin-5 (IL-5) is also known as B-cell growth factor II. In addition to stimulating B cell expansion and the secretion of antibodies, IL-5 possess a number of other functions that have implications for the host immune response to infection and allergy. The location of the IL-5 gene (chromosome 5) is near the genes that regulate IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF), which are often expressed alongside IL-5 on T helper 2 (Th2) cells. IL-5 expression is modulated by a number of different transcription factors including, but not limited to, GATA3.
IL-5 is perhaps best known for its role in promoting allergic responses. IL-5 regulates the activation of granulocytes involved in generating allergic inflammation, namely eosinophils. Non-allergic conditions that involve excessive eosinophil production, such as Hodgkin lymphoma, are also exacerbated by IL-5 signaling. In addition to eosinophils, IL-5 is expressed on mast cells which degranulate in response to the detection of allergens, further increasing localized vasodilation and inflammation. Given its contribution to allergic diseases through promoting eosinophilia, IL-5 is a target for drugs designed to treat severe eosinophil-driven allergic and asthmatic conditions.
Although much of the research on IL-5 has focused on its contribution to allergic pathology, it is also important for the immune response to infectious microorganisms. For example, Th2-dominant cytokines, such as IL-5, play an important role in the body’s defenses against parasites, such as Toxocara canis. In enhancing B cell growth and antibody production, IL-5 also acts as a link between the innate and adaptive immune systems. IL-2 can be measured in both saliva and blood. The extent to which serum / plasma and salivary levels of this cytokine correlate is yet to be confirmed.
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