IL-4 Protein, Human (HEK293, hFc)

The cytokine IL-4, primarily secreted by mast cells, T-cells, eosinophils, and basophils, plays a crucial role in regulating antibody production, hematopoiesis, inflammation, and the development of effector T-cell responses. IL-4 induces the expression of class II MHC molecules on resting B-cells and enhances both the secretion and cell surface expression of IgE and IgG1, contributing to immune responses. Additionally, IL-4 regulates the expression of the low-affinity Fc receptor for IgE (CD23) on both lymphocytes and monocytes and positively regulates IL31RA expression in macrophages. Furthermore, IL-4 stimulates autophagy in dendritic cells by interfering with mTORC1 signaling and inducing RUFY4. Beyond its immunological functions, IL-4 plays a critical role in higher functions of the normal brain, such as memory and learning. Upon binding to its receptor, IL-4R, IL-4 initiates signaling through two types of receptor complexes, type 1 mainly on hematopoietic cells and type 2 on nonhematopoietic cells, activating JAK3 and to a lesser extent JAK1 phosphorylation, leading to the activation of the signal transducer and activator of transcription 6/STAT6. IL-4 interacts with both IL-4R and IL13RA1 to mediate its diverse physiological effects.