IL-13(Interleukin-13) is a pleiotropic cytokine that plays a crucial role in immune regulation and inflammation, exhibiting approximately 30% sequence identity with IL-4 and sharing many biological activities. IL-13 is primarily secreted by activated T lymphocytes and significantly influences monocytes, macrophages, and B cells by upregulating CD23 and major histocompatibility complex proteins while downregulating CD14. IL-13 is involved in inhibiting proinflammatory cytokines and chemokines from activated monocytes, as well as stimulating IgE expression on activated B cells, making IL-13 a key player in allergic responses and asthma. IL-13′s structure includes five cysteine residues, which are essential for stability and function, and multiple N-linked glycosylation sites that are critical for biological activity and interaction with receptors.