Dosage of serum tryptase levels which is easily accessible and the work by Vitte let us imagine that the younger the child, the greater the mast cell expression, thus opening a capital pathway in the comprehension of immune system phenomena in premature babies and investigators can hope that by performing regular workups of serum tryptase levels, investigators could validate that some premature babies will express this activity in a more important manner. The relationship to eventual pathological phenomena such as necrotizing enterocolitis, but also bronchopulmonary dysplasia could then be highlighted.