[Molecular mechanism of apoptosis operated in the immune system].

Apoptosis is the physiological cell death, and plays an important role in the various fields of immunology, especially (1) in the formation of T cell and B cell repertoires, (2) in the regulation of hyper-activated T and B cells by Fas-FasL, and (3) in the effector phases of eliminating potentially dangerous cells. Although, the exact mechanism of cell death is still unknown, progress has been made in identifying key elements in apoptosis. Particularly, ICE family was found essential for apoptotic execution, and Bcl-2 related proteins can block the molecular events of apoptosis. This article briefly reviewed such "on" and "off" signals in apoptosis, and discussed from the view point that the disturbance of the balance of these signals are relevant to the etiology of autoimmune diseases.