Whereas human newborns are protected during the first months of life against bacterial infections owing to maternal antibodies which cross the placental barrier or are transmitted by breast milk, their immature system is unable to afford efficient protection against infections caused by pathogens for which defenses merely depend on T lymphocytes. As a consequence, infections by respiratory syncytial virus (RSV), herpes simplex virus (HSV), human immunodeficiency virus (HIV), human cytomegalovirus (HCMV), Mycobacterium tuberculosis and Plasmodium falciparum are often severe in early life, especially in developing countries. The development of efficient vaccines against these diseases therefore requires circumventing the immaturity of the immune system in early life. In industrialized regions, the growing incidence of allergic diseases such as atopic dermatitis and bronchial asthma and of autoimmune diseases such as type I diabetes is also related to unique features of the infant immune responses. On the other hand, differences between neonatal and adult immune responses explain the benefit of cord blood transplants for the treatment of haematological malignancies.

IMI scientists conduct experimental and clinical investigations which aim to the definition of the cellular and molecular bases of the immaturity of the newborn immune system, focusing on dendritic cells and T lymphocytes. In parallel, they build on the knowledge generated on vaccine adjuvants to assess innovative strategies to accelerate the maturation of immune responses in early life.