CD124, also known as the α subunit of IL-4R, is a 140 kD transmembrane glycoprotein. It associates with either the common γ-chain (CD132) to form the type I IL-4R complex, which specifically binds IL-4, or with IL-13Ra1 to form the type II IL-4R heterodimeric complex, which binds and transduces signals from either IL-4 or IL-13.  A truncated form of IL-4Rα exists in the soluble form in biological fluids. CD124 is expressed on human B and T cells as well as a variety of other hematopoietic and non-hematopoietic cells and cell lines.  In B cells, CD124 can bind with IL-4 and IL-13 to regulate IgE antibody production. In T cells, the type I IL-4R (IL-4R/gC) is mostly responsible for Th2 cell expansion by mediating IL-4-dependent activation of the transcription factors in hematopoietic cells. The type II IL-4R (IL-4R/IL-13Ra1) is the main route for non-hematopoietic cell responses to IL-4 or IL-13.

Each lot of this antibody is quality control tested by immunofluorescent staining with flow cytometric analysis. For flow cytometric staining, the suggested use of this reagent is ≤1.0 microg per million cells in 100 microL volume. It is recommended that the reagent be titrated for optimal performance for each application.