IL-16(Interleukin 16) is a pleiotropic cytokine that functions as a chemoattractant, a modulator of T cell activation, and an inhibitor of HIV replication. IL-16 plays a crucial role in the immune response as a cytokine with chemoattractant properties specifically for CD4+ T lymphocytes. IL-16 is secreted by activated eosinophils during allergic reactions, contributing to the recruitment of immune cells to sites of inflammation. IL-16 interaction with CD4 receptor triggers a signaling cascade that activates protein kinase C (PKC) pathways, leading to various physiological changes in target cells. Understanding IL-16 function is vital, as IL-16 not only mediates the inflammatory response but also helps elucidate the underlying mechanisms of allergic diseases, making IL-16 a significant target for therapeutic interventions.