Senescent cell antigen: a terminal differentiation antigen

Investigations into mechanisms by which macrophages distinguish mature from senescent self cells revealed that a approximately 62,000 Mr glycoprotein, the senescent cell antigen, a terminal differentiation antigen, appears on the surface of senescent and damaged cells. It is recognized by the antigen-binding Fab region of a specific IgG autoantibody in serum which attaches to cells carrying the senescent cell antigen and initiates their removal by macrophages. The senescent cell antigen was first observed on the surface of senescent human erythrocytes, but has since been demonstrated on the surface of lymphocytes, polymorphonuclear leukocytes, platelets, embryonic kidney cells and adult liver cells.