MERTK and systemic lupus erythematosus: Because production of anti-Ro60 antibodies represents a lupus-specific humoral autoimmune response against early ACs [48] and MerTK is specifically required for M2c macrophage phagocytosis of early ACs [9], the strong association that we found between anti-Ro60 and sMer in SLE patients might reflect a compensatory increase in M2c activation of monocytes and/or macrophages to enhance the clearance of early ACs by MerTK.