Effects of environmental tobacco smoke on the developing immune system of infant monkeys

BackgroundExposure to environmental tobacco smoke (ETS) is associated with an increased incidence of allergic and infectious diseases among children that is thought to be partly due to the immaturity of the immune system.ObjectiveWe sought to investigate the effects of ETS exposure on immune development during the first year of life in the nonhuman primate.MethodsFifteen neonatal rhesus monkeys studied to 13 months of postnatal age were randomized into 3 groups: (1) exposure to filtered air, (2) continuous ETS exposure beginning at gestation day 50 (perinatal ETS); and (3) exposure to ETS beginning at 6 months of age (6-month ETS). Complete blood counts, lymphocyte subsets, and mRNA levels of 12 cytokines in PBMCs were measured.ResultsFetal/infant exposure to ETS altered the normal maturation of mRNA levels of IFN-γ, IL-2, and IL-10, as well as the ratio of CD4 to CD8 lymphocytes, compared with filtered-air control levels. Blood lymphocyte subset distribution also significantly differed based on the onset of exposure to ETS. Subacute exposure to ETS for 2 weeks in 6-month-old infants was found to increase levels of peripheral blood neutrophils and IL-6 mRNA.ConclusionsShort-term exposure to ETS can induce an acute systemic inflammatory response in the neonatal nonhuman primate, and long-term exposure to ETS beginning in utero or at 6 months of postnatal age can significantly alter immune effectors.Clinical implicationsNormal immune system development is compromised by in utero and postnatal exposure to ETS and might contribute to ETS-related childhood diseases.