This gene encodes the alpha chain of the interleukin-4 receptor, a
type I transmembrane protein that can bind
interleukin 4 and
interleukin 13 to regulate
IgE antibody production in
B cells. Among
T cells, the encoded protein also can bind interleukin 4 to promote differentiation of
Th2 cells. A soluble form of the encoded protein can be produced by an alternate splice variant or by proteolysis of the membrane-bound protein, and this soluble form can inhibit IL4-mediated cell proliferation and IL5 upregulation by T-cells. Allelic variations in this gene have been associated with atopy, a condition that can manifest itself as allergic rhinitis, sinusitis, asthma, or eczema. Two transcript variants encoding different isoforms, a membrane-bound and a soluble form, have been found for this gene. Interactions of IL-4 with
TNFα promote structural changes to vascular endothelial cells, thus playing an important role in tissue inflammation. The binding of IL-4 or IL-13 to the IL-4 receptor on the surface of
macrophages results in the alternative activation of those macrophages. Alternatively activated macrophages (AAMΦ) downregulate inflammatory mediators such as
IFNγ during immune responses, particularly with regards to
helminth infections. == Interactions ==