Don't be such a baby! or the effects of the environment and T cells on neonatal immunity [abstract]

Abstract

It is known that neonates are highly susceptible to microbial infections and allergic reactions. This susceptibility is due to a lack of Th1 cells and an excess of its Th2 counterparts. However, the mechanism underlying this Th1/Th2 imbalance has not been clearly elucidated. Although both Th1 and Th2 cells are present in the primary response, only Th1 cells up-regulate the IL- 13R[alpha]1 chain. Consequently IL-13R[alpha]1 can associate with IL-4R[alpha] to form a heteroreceptor through which IL-4 from Th2 cells can signal and cause the apoptosis of Th1 cells upon secondary re-challenge with antigen. Formation of this IL-13R[alpha]1/IL-4R[alpha] heteroreceptor is influenced by two factors: the neonatal environment and intrinsic T cell factors.