CD38 expression by neonatal human naive CD4+ T cells shapes their distinct metabolic and tolerogenic properties.

Neonatal life is marked by rapid antigen exposure, necessitating establishment of peripheral immune tolerance via conversion of naive CD4+ T cells into Tregs. We demonstrated heightened capacity for FOXP3 expression and tolerogenic function among cord blood versus adult blood naive CD4+ T cells. Further, this was linked to a distinct cord blood metabolic profile and elevated neonatal expression of the NADase, CD38. Early-life naive CD4+ T cells demonstrated a metabolic preference for glycolysis, which directly facilitated their differentiation trajectory. We revealed an age-dependent gradient in CD38 levels on naive CD4+ T cells and showed that high CD38 expression contributes to the glycolytic state and tolerogenic potential of neonatal CD4+ T cells, effects mediated at least partly via the NAD-dependent deacetylase SIRT1. Thus, the early-life window for peripheral tolerance in humans is critically enabled by the immunometabolic state of the naive CD4+ compartment.