Phenotypic and functional studies of NK cells in neonates and during early childhood

Abstract: During infancy, before adaptive immunity has matured, innate immunity is thought to be relatively more important. Human natural killer (NK) cells are innate immune cells involved in the control of virus-infected cells and can influence adaptive immunity mainly through cytokine production. This thesis aimed at investigating function and phenotype of NK cells in children from birth and during early childhood and to see if these features are altered in children that develop early allergy, in children latently infected by herpes viruses or born by preeclamptic mothers.Our results suggest that NK-cell populations are dynamic during the first years of life and start to resemble the phenotype of adults after five years of age. Early alterations in the NK-cell populations could lead to insufficient Th1 priming, with an increased risk to develop allergic disease. Early infection by common herpes viruses can influence NK-cell function and might be one important factor involved in early maturation processes of adaptive immunity. The altered NK-cell function and cytokine levels, noticed in CB from pathological pregnancies, suggest that NK cells could be influenced already in utero. These early alterations of innate immunity may affect the development of the child’s immune system, sometimes with beneficial outcome but could in some cases promote pathology.