Neonatal immune function and early immune development in children born in traditional versus modern environments

[Truncated abstract] Background: The incidence of chronic inflammatory diseases including allergy and autoimmunity has risen dramatically in industrialized countries over the last few decades. Similar trends are now being observed in human populations transiting from traditional to more modern or ‘westernized’ lifestyles; suggesting that a traditional environment and/or lifestyle is protective. Accordingly, there is increasing evidence that environmental exposures in early life, including prenatal life, can affect the course of early immune development and hence risks for the development of immunological disease. Still, relatively little is known about neonatal immune function and the process of early immune development in children born under traditional lifestyle conditions and how this compares to children born in modern environments. Hypotheses: In line with the ‘hygiene hypothesis’, we expected to find evidence of enhanced immuno-regulatory mechanisms in neonates born in traditional compared to modern environmental settings. Furthermore, we hypothesized that the trajectory of early immune development in traditional populations might differ from that reported for westernized populations, and is influenced by relevant in utero exposures such as the microbial experience of the mother during pregnancy. Methods: Cord blood mononuclear cells (CBMC) collected from neonates born under traditional (Papua New Guinea; PNG) and modern living conditions (Australia; AUS) were quantitatively and qualitatively compared for differences in T regulatory (Treg) cells, T-helper (Th) cells and antigen presenting cells (APC). When PNG infants were aged between 1-18 months old they were followed-up once more and innate immune responses to a range of Toll-like (TLR) and NOD-like receptor (NLR) ligands were measured using whole blood assays.