In this thesis, new insights in the complex and intertwined relationship between viral infections, T cells and natural killer cells after allogeneic HSCT in children are provided and discussed.... Show moreIn this thesis, new insights in the complex and intertwined relationship between viral infections, T cells and natural killer cells after allogeneic HSCT in children are provided and discussed. Patients are at high risk of viral complication during the T cell deficient period early after HSCT. When viral infections occur, interventions to bridge the period until the recovery of antiviral T cell immunity are of great importance to improve the clinical outcome after HSCT. Besides antiviral medication and the use of adoptive immunotherapy, NK cells may play a role in the protection against viruses when T cells are not available to perform their task. Show less