Both Mepolizumab and reslizumab bind to interleukin-5 (IL-5), a key cytokine responsible for the differentiation, maturation, and activation of human eosinophils. Both antibodies bind to IL-5 and prevents binding to the interleukin 5 receptor alpha subunit, on the surface of eosinophil white blood cells. When these antibodies bind to IL-5, they stimulates B cell growth and increases immunoglobulin secretion, and this reduces the survival of eosinophils. Eosinophils, along with basophils and mast cells, are important mediators of allergic responses and severe asthmas.
