Is SLE a disease of defective clearance of apoptotic cells?
Recent studies have emphasised that apoptotic cells are not immunologically inert, but rather have either positive or negative effects, depending on the antigen-presenting cell with which they interact. Is autoimmunity simply caused by an increase in the load of autoantigens? For example, dendritic cells have been shown to be able to phagocytose apoptotic cells via the αvβ5 receptor [17] and afterwards efficiently present antigens derived from apoptotic cells to MHC class I- and II-restricted T cells [17,18,19] in a dose-dependent manner [20]. When macrophages are also present, the presentation of apoptotic cells is markedly inhibited. Two possible mechanisms might explain this inhibition. One is that phagocytosis of apoptotic cells by macrophages is so rapid and so efficient that the amount of apoptotic material ingested by dendritic cells is minimised. The other is that phagocytosis of apoptotic cells by macrophages induces the production of anti-inflammatory cytokines (e.g. transfor
