Apoptosis plays a fundamental role in maintenance of homeostasis of the immune system. Many experiments in vitro and in vivo show that in systemic lupus erythematosus there are disturbances in the process of clearance of apoptotic cells. That leads to prolonged exposure of the immune system to autoantigens and to the development of autoimmunity. Nowadays this process is put forward as a core mechanism in the pathogenesis of this disease. Possible factors which may influence disturbances in the clearance of apoptotic cells are: deficiency of complement, decreased levels of MBL protein and DNAase, low levels of C reactive protein and some antibodies (antibodies against acute phase proteins and against the components of complement).