CD127, also known as the interleukin-7 receptor alpha chain (IL-7Rα) or simply the IL-7 receptor, is a transmembrane glycoprotein primarily expressed on the surface of T cells, B cells, natural killer (NK) cells, as well as certain hematopoietic stem cells and progenitor cells. Upon binding to IL-7, CD127 activates a series of signaling pathways, including the JAK-STAT cascade, which subsequently promotes the growth and differentiation of lymphocytes. This interaction is particularly crucial during the development of T and B cells within the thymus and bone marrow, as it aids in their progression from early progenitor stages to maturity. Furthermore, the expression level of CD127 serves as an indicator for assessing lymphocyte function and status.