[From Ipex to foxp3: a new contribution of pediatrics to the understanding of the immune system].

In 10 years, the neonatal autoimmune enteropathy has been individualized from other causes of neonatal severe protracted diarrheas as a syndrome called Ipex for Immunodysregulation, Polyendocrinopathy, Enteropathy, X-linked. Thanks to linkage analyses in affected families, this rare paediatric syndrome with fatal outcome has been correlated to mutations of the foxp3 gene. Homozygous loss of function of foxp3 gene results in the absence of development of a crucial subpopulation of lymphocytes with CD4+CD25+ phenotype, called regulatory T-cells. The study of these lymphocytes allows a better understanding of the immune system homeostasis and of the physiopathology of Ipex syndrome, which is a prerequisite for treatment. Achieving ex vivo manipulation of such lymphocytes will end up on promising applications of cell therapy.