It became evident that IL-15 contributes to the cytotoxic potential of CTL by increasing the expression of NKG2D and its adaptor DAP10 in CD8+ T cells, and indeed, patients with active CeD display a 4- to 20-fold higher expression of NKG2D on intraepithelial CTL, when compared with healthy individuals (18). This evidence concerns the gene HCST and cranioectodermal dysplasia.