title: Natural killer cell responses to infections in early life.
abstract: Natural killer (NK) cells are an important component of innate immune responses to infectious diseases. They mediate protection by being able to rapidly lyse infected cells and produce cytokines (primarily interferon-γ) that shape innate and adaptive immune responses. This review summarizes current knowledge on the phenotype and functional abilities of NK cells from healthy newborns/infants and on NK cell responses against viral, bacterial and protozoan infections in early life. Interestingly, NK cell blood counts are higher in newborns than in adults but they do not display striking differences in phenotype, except for an increased frequency of expression of the inhibitory CD94/NKG2A receptor. They display some inherent functional defects, mainly a lower cytolytic capacity that may contribute to the immaturity of the neonatal immune system. Changes in circulating levels of NK cells observed during pediatric infections and the ability of NK cells from newborns and children to produce interferon-γ at the encounter with pathogens indicate that NK cells participate in the immune response to infectious diseases in early life. Unfortunately, information is currently insufficient to assess whether these NK cell responses really contribute to control infections, either vertically transmitted or acquired in infancy.
authors.affiliation: Laboratoire de Parasitologie, Faculté de Médecine, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Aline
authors.initials: A
authors.lastname: Guilmot
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Hermann
authors.forename: Véronique M
authors.initials: VM
authors.lastname: Braud
authors.forename: Yves
authors.initials: Y
authors.lastname: Carlier
authors.forename: Carine
authors.initials: C
authors.lastname: Truyens
mesh_terms: D002452:Cell Count; D006801:Humans; D007113:Immunity, Innate; D007231:Infant, Newborn; D007239:Infections / Q000276:immunology*; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control; D007371:Interferon-gamma / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation; D055654:NK Cell Lectin-Like Receptor Subfamily C / Q000276:immunology
chemical_list: D055654:NK Cell Lectin-Like Receptor Subfamily C; D007371:Interferon-gamma