Interleukin-13 (IL-13) is an important cytokine secreted from Th2 cells. The functions attributed to IL-13 overlap significantly with those of IL-4 (induces IgE secretion from B cells and inhibits expression of inflammatory cytokines such as IL-1 beta, TNF- alpha , IL-8 and IL-6), but differs from IL-4 in that IL-13 seems to link inflammatory response of immune cells to the pathophysiological changes in the surrounding non-immune cells. The receptor subunits of IL-13 consist of IL-4R alpha , IL-13R alpha 1 and IL-13R alpha 2. and IL-13 are cross-reactive. Recombinant IL-13 is a non-glycosylated Protein, containing 114 amino acids, with a molecular weight of 12.5 kDa.