Central Tolerance Matters

In this issue of Immunity, Anderson et al. provide another clue to the riddle that is Aire—why do human beings and mice lacking Aire develop diffuse and pathogenic autoimmunity? They find that Aire influences central tolerance not only by promoting the expression of peripheral self-proteins in thymic medullary epithelial cells (MECs) but also by furnishing these cells with the apparatus for effective antigen presentation (Anderson et al., 2005)