Detection of Recombinant Rat IL‑13 by Western Blot. Western blot shows 25 ng of Recombinant Rat IL‑13 (Catalog # 1945-RL), Recombinant Human IL‑13 (Catalog # |
213-ILB) and Recombinant Mouse IL‑13 (Catalog # 413-ML). PVDF Membrane was probed with 0.1 µg/mL of Goat Anti-Rat IL‑13 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF1945) followed by HRP-conjugated Anti-Goat IgG Secondary Antibody (Catalog # HAF109). A specific band was detected for IL‑13 at approximately 10 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 3.
Cell Proliferation Induced by IL‑13 and Neutralization by Rat IL‑13 Antibody. |
Recombinant Rat IL‑13 (Catalog # 1945-RL) stimulates proliferation in the TF‑1 human erythroleukemic cell line in a dose-dependent manner (orange line). Proliferation elicited by Recombinant Rat IL‑13 (15 ng/mL) is neutralized (green line) by increasing concentrations of Goat Anti-Rat IL‑13 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF1945). The ND50 is typically 0.2-0.8 µg/mL.
IL-13 is a 17 kDa immunoregulatory cytokine that plays a key role in the pathogenesis of allergic asthma and atopy. It is secreted by Th1 and Th2 CD4+ T cells, NK cells, visceral smooth muscle cells, eosinophils, mast cells, and basophils. IL-13 circulates as a monomer with two internal disulfide bonds that contribute to a bundled four alpha -helix configuration. Mature rat IL-13 shares 59%, 75%, and 60% amino acid sequence identity with human, mouse, and rhesus IL-13, respectively. Despite the low homology, it exhibits cross-species activity between human, mouse, and rat. IL-13 has diverse activities on numerous cell types. On macrophages, IL-13 suppresses the production of proinflammatory cytokines and other cytotoxic substances. On B cells, IL-13 induces immunoglobulin class switching to IgE, upregulates the expression of MHC class II, CD71, CD72, and CD23, and costimulates proliferation. IL-13 upregulates IL-6 while downregulating IL-1 and TNF-alpha production by fibroblasts and endothelial cells. IL-13 binds with low affinity to IL-13 R alpha 1, triggering IL-13 R alpha 1 association with IL-4 R alpha. This high affinity receptor complex also functions as the type 2 IL-4 receptor complex. Additionally, IL-13 binds with high affinity to IL-13 R alpha 2 which is expressed intracellularly, on the cell surface, and as a soluble molecule. IL-13 R alpha 2 regulates the bioavailability of both IL-13 and IL-4 and is over-expressed in glioma and several bronchial pathologies. Compared to wild type IL-13, the atopy-associated R110Q variant of IL-13 elicits increased responsiveness from eosinophils that express low levels of IL-13 R alpha 2.