Cell Intrinsic Characteristics of Cord Blood Naive CD4 T Cells

The neonatal immune system is functionally distinct from the adult immune system. Neonatal immune responses are less reactive than their adult counterparts, and as such, have an increased susceptibility to infection, resulting in increased duration and severity of disease. There is evidence that T-cells are partially responsible for the observed immunological differences between neonates and adults. Murine studies on neonatal immunity suggest that Th2 like responses predominate the neonatal immune system, an observation not found in the adult immune system. However, studies on human cord blood revealed that human neonates do not exhibit elevated Th2 like cytokines (with the exception of IL-13) when compared to adults, raising the question of whether or not neonatal T-cells are fundamentally different from adult T- cells. We sought to explore potential differences between neonatal and adult T-cells through the comparative analysis of naïve CD4 T-cells derived from cord blood and adult peripheral blood. Our data reveals that cord blood naïve CD4 T-cells have significantly higher expression of CD26. Additionally, cord blood T-cells have a greater capacity to produce Th1/Th2 cytokines than adult T-cells when prompted to differentiate into effector cell types. Additionally, undifferentiated naïve T-cells from cord blood are less responsive to stimulation than adult T-cells, however this decreased activity is likely not due to reduced expression of signaling molecules in neonatal naive T-cells