Hungarian Immunology

[Neonatal activation of interferon-γ in macrophages]

ERDŐS Melinda, MARÓDI László

MARCH 20, 2002

Hungarian Immunology - 2002;1(01)

[Each individual passes through developmental or transient immunodeficiency due to the immaturity of the immune system in early childhood, expecially in the neonatal period. Therefore, neonates contract infections by intracellular and extracellular microorganisms more easily than older children and adults, and develop more severe disease with a high mortality rate. A number of abnormalities in the neonate’s host defense systems have been described suggesting that the immune system at birth functionally differs from that in adults. Neonatal T and B cells show decreased reactivity to antigens and mitogens and have deficienct IgM-IgG isotype switching. Newborns have decreased functional capacities of the hemolytic complement system. Under the same in vitro and in vivo conditions neonatal granulocytes show functional deficiency earlier than adult cells. Effector mechanisms of the cell-mediated immunity involve activation of macrophages by T helper1 cytokines, particularly interferon- γ (IFN-γ). IFN-γ is the most important macrophage-activating cytokine in vivo. Neonatal T cells express lower levels of IFN-γ and macrophages are hyporesponsive to activation by this cytokine. This deficiency may be explained by decreased phosphorilation of STAT1 despite comparable expression of STAT1 protein in neonatal and adult macrophages.]

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