In fact, an intact classical complement pathway is essential for the phagocytic removal of apoptotic cells [46], whereas the deficient ApoCell-phagocytosis in SLE patients has been previously attributed to defective opsonization of apoptotic cells by aberrantly low levels of C1q, C3, and C4 complement proteins [17]. This evidence concerns the gene C4A and systemic lupus erythematosus.