Apoptosis: Mechanisms of life and death in the immune system

When normal cells die, it is almost always by the process of apoptosis, whi ch is a morphologic description. Some cells die readily and are rapidly rep laced; others live as long as we do. Because apoptotic morphology is simila r from cell to cell, researchers have embarked on an intense search for a c ommon underlying biochemical process. There is an apoptotic mechanism or ce ll death program, which is expressed in embryos and throughout life. Most t issues, and especially the skin, gut, and immune system, depend on well-ord ered apoptosis and cell replacement. Apoptosis can fail to occur, as in the newly described autoimmune lymphoproliferative syndrome, or be turned on p athologically, as in degenerative diseases, We would like to induce apoptos is in dangerous cells or block it to preserve valuable cells. We need to kn ow more about how apoptosis is regulated and what we can do to influence th e process.