Apoptosis
Each day, 10 million cells undergo programmed cell death (apoptosis) in a healthy individual.
The mechanism is necessary to control tissue size and homeostasis without inciting inflammation. The two pathways leading to apoptosis are listed in the previous question. During apoptosis, the chromatin condenses, cells shrink, and cell membranes form blebs that become apoptotic bodies containing organelles. The cell membrane is inverted and the phosphatidylserine in the membrane signals macrophages to phagocytose the apoptotic bodies causing them to release antiinflammatory cytokines. Binding of C1q, collectins and MBL to apoptotic cells can facilitate their clearance.
