Background：CD7 is a 40 kD type I transmembrane glycoprotein also known as gp40. It is a member of the immunoglobulin superfamily found on T cells, NK cells, thymocytes, hematopoietic progenitors, and monocytes （weakly）. CD7 is also expressed on acute lymphocytic leukemia （ALL） and some acute myeloid leukemia （AML） cells. CD7 crosslinking induces a calcium flux in T lymphocytes, presumably as a result of cytoplasmic domain association with PI3-kinase. CD7 costimulation can induce cytokine secretion and modulate cellular adhesion.
