It has been reported that interleukin 2 (IL)2-deficient mice have an impaired T cell lymphopoiesis in the gut and that the intestinal inflammation seen in these mice was caused by thymus-derived T cells.28 It is possible that the local T cell maturation also generates regulatory intestinal T cells in humans, in which case the reduced extrathymic T cell maturation in patients with coeliac disease would cause a reduced capacity to downregulate gluten-reactive, thymus-derived T cells in the intestinal mucosa. The gene discussed is IL2; the disease is celiac disease.