Apoptosis and systemic autoimmunity: the dendritic cell connection

Much effort has been devoted in recent years to the events linking recognit ion and disposal of apoptotic cells to sustained immunity towards the antig ens they contain. Programmed death via apoptosis indeed provides most of th e raw material the immune system exploits to establish self tolerance, i.e. to learn how to distinguish between self constituents and foreign antigens , belonging to invading pathogens. In parallel, events occurring during cel l death may enable a restricted array of molecules endowed with diverse str ucture, function and intracellular distribution to satisfy the requirement to evoke and maintain autoimmune responses. Dendritic cells (DCs), the most potent antigen presenting cells, appear to play a crucial role. Here we wi ll discuss some of the constrains regulating the access of dying cells' ant igens to DCs, as well as censorship mechanisms that prevent their maturatio n and the full explication of their antigen presenting function.