Table 1.

Potential Impact of Populations/Processes Either Differentially Represented in or Unique to the Neonate

Cell Subset/Process	Potential Consequences
Developmental specific epigenetic patterns at the Th2 and Th1 locus	Rapid development of robust Th2 function (mouse); persistence of low level Th2 function in Th1 cells (human); typically reduced Th1 responses (human)
↑ homeostatically proliferating cells	Natural memory population; both Th1 and Th2 rapid effector activity; may provide mature levels of protection against cross-reactive exogenous antigens (human, mouse)
↑ fetal origin cells	Robust cytokine production; variable Th1/Th2 ratios, depending on antigen concentration (mouse) or unknown conditions (human)
↑ RTE	Variable IL-2, IL-4 production and proliferation
↑ cells with forbidden TCR	May contribute to early life autoimmunity but also to responses against cross-reacting infectious agents
↓ Treg activity/numbers	May modulate the development of either Th1 or Th2 function
↑ TCR with no N region	Promiscuous reactivity, beneficial in infections; Low affinity or reduced reactivity to self-antigens, protective against autoimmunity