Sanne Hoeks

Chapter 7 108 It can be concluded that different T cell populations develop uniquely with age. During the first year, T cell differentiation occurs under supervision of Tregs which are still highly present at twelve months of age. The capacity to differentiate into effector T cells like T H 17 increases after the first three months of life together with the change in adult-like phenotype of antigen- presenting cells and other strong effector immune responses. This might implicate that the concept of immune development within a window of opportunity must be implemented into a model with a place for subsequent phases that might depend on each other to facilitate the establishment of a mature, homeostatic but vigilant immune system. 36