Description
Interleukin-5 (IL-5) is a secreted glycoprotein that belongs to the alpha -helical group of cytokines. Unlike other family members, it is present as a covalently linked antiparallel dimer. The cDNA for rat IL-5 encodes a signal peptide and a 113 amino acid (aa) secreted mature protein. Mature rat IL-5 shares 70%, 94%, 56%, 63%, 59% and 59%, aa sequence identity with human, mouse, canine, equine, feline and porcine IL-5, respectively. IL-5 is primarily produced by CD4+ Th2 cells, but also by activated eosinophils, mast cells, EBV-transformed B cells, Reed-Sternberg cells in Hodgkin’s disease, and IL-2-stimulated invariant natural killer T cells (iNKT). IL-5 increases production and mobilization of eosinophils and CD34+ progenitors from the bone marrow and causes maturation of eosinophil precursors outside the bone marrow. The receptor for human IL-5, mainly expressed by eosinophils, but also found on basophils and mast cells, consists of a unique ligand-binding subunit (IL-5 R alpha) and a shared signal‑transducing subunit, beta c. IL-5 R alpha first binds IL-5 at low affinity, then associates with preformed beta c dimers, forming a high-affinity receptor. IL-5 also binds proteoglycans, potentially enhancing its activity. Soluble forms of IL-5 R alpha antagonize IL-5 and can be found in vivo. In humans, IL-5 primarily affects cells of the eosinophilic lineage, and promotes their differentiation, maturation, activation, migration and survival, while in mice IL-5 also enhances Ig class switching and release from B1 cells. IL-5 also promotes differentiation of basophils and primes them for histamine and leukotriene release.
Biological Activity
The ED50 as determined by a cell proliferation assay using human TF-1 cells is less than 0.5 ng/mL, corresponding to a specific activity of > 2.0 × 106 IU/mg. Fully biologically active when compared to standard.
Reconstitution
We recommend that this vial be briefly centrifuged prior to opening to bring the contents to the bottom. Reconstitute in sterile distilled water or aqueous buffer containing 0.1% BSA to a concentration of 0.1-1.0 mg/mL. Stock solutions should be apportioned into working aliquots and stored at ≤ -20°C. Further dilutions should be made in appropriate buffered solutions.