Although neonatal life is characterized by heightened susceptibility to infectious agents, early microbial signals are essential to the maturation of the adaptive immunity. Refering to the hygiene hypothesis, the activation of CD8+ T lymphocytes of variable specificity at the beginning of life, by preventing a Th2 skewed pattern for the T lymphocytes, could prevent the emergence of allergic pathologies. In a model of neonatal immunization, François Mahieu and his research team focused their study on the role of the interleukins (IL) of the IL-12 family, particularly on the still poorly investigated IL-23 and IL-27, that would be produced in response to "toll-like" receptor ligands as adjuvants in the control of the emergence of allergic pathologies