Inflammation and the apopto-phagocytic system.

Although under normal conditions many cells die daily mainly by apoptosis in human tissues, inflammation does not occur. The redundant function of a relatively large number of molecules are available to recognize changes occurring on the surface of apoptotic cells, to opsonize the dead cells and to engulf the apoptotic cells previously opsonized or not. Several components of the innate immune system are utilized in this process, mainly soluble factors which bind to the distinct molecular pattern of apoptotic cells. These cells, unlike necrotic ones, do not induce the expression of inflammatory cytokines in phagocytic cells, they can even inhibit such a response and engage an active signaling process to elicit a direct anti-inflammatory effect. The molecular details of these signaling processes have not been clarified yet. Both professional and "amateur" cells can engulf apoptotic cells and mediate an anti-inflammatory action. Disturbance of these processes have significant roles in development of autoimmune diseases and highly malignant tumors.