The studies reported here enhance the current knowledge on the in vitro and in vivo activities of FcF241A and FcAbdeg, demonstrate that their mechanisms of action are distinct (FcF241A and IVIG exert immune protection through SIGN-R1/DC-SIGN while FcAbdeg does not), and illustrate their potential utility in the treatment of autoimmune conditions. This evidence concerns the gene CD209 and Autoimmunity.