Background：CD127 is a 60-90 kD type I transmembrane glycoprotein also known as IL-7 receptor a chain or IL-7Ra. It forms a heterodimer with the common gamma chain （gammac or CD132） which is shared with the receptors for IL-2, IL-4, IL-9, IL-13, IL-15, and IL-21. CD127 is expressed on immature B cells through early pre-B stage, thymocytes （except CD4/CD8 double positive thymocytes）, peripheral T cells, and bone marrow stromal cells. CD127 has been reported to be an useful marker for identifying memory and effector T cells. The ligation of IL-7 with its receptor is important for stimulation of mature and immature T cells as well as immature B cells proliferation and development.
