Interleukin 4 (IL-4) is present in various forms with molecular weights ranging between 15 and 19 kDa, differences due to variable glycosylation of the molecule. The human IL-4 gene is located on the long arm of chromosome 5 in close association with the genes for IL-13, IL-5, GM-CSF and IL-3.
IL-4 performs its function by binding to receptors expressed on the target cells. Its receptors are present in B- and T-cells as well as in macrophages. In T- and B-cells, the receptors are in low numbers (about 400) but may increase under the influence of IL-2 and IL-4.
IL-4 is produced by a specific subset of T helper cells, the Th2 cells. These cells tend to produce a specific set of lymphokines, including IL-4, IL-5, IL-6, IL-10, IL-13, IL-3 and GM-CSF and cannot produce IL-2, IFN-γ and lymphotoxin (TNF-β). In addition to T-cells, it has been shown that mast cells and basophils can also produce IL-4.
IL-4 exhibits different effects on different hematopoietic cell types. On B-cells, IL-4 promotes immune change of antibodies against IgE and IgG1 and regulates MHC class II expression and CD23 expression. It can promote the survival, growth and differentiation of both T- and B-cells, mast cells and endothelial cells. In addition, IL-4 can inhibit the production of TNF-α, IL-1 and IL-6 by macrophages. IL-4 also has antitumor activity both in vivo and in vitro.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.