Table 4:

Adaptive immune cells in infants, and comparison with adults

Type of cells	Difference from adults	References
T helper 1 (Th1) cells	Lower CD40 ligand (CD40L) expression (lower B cell response). Lower IFN-γ secretion.	55,60
T helper 2 (Th2) cells	Higher anti-inflammatory cytokine (IL-4, IL-5, and IL-10) secretion.	38
Cytotoxic T (Tc) cells	Lower cytotoxic function due to lower CD80/CD86 expression and lower IL-12 secretion by antigen-presenting cells (APCs).	72
T regulatory cells (Tregs)	Higher numbers in human cord blood (∼12% of CD4+ T cells) and neonatal lymph nodes (∼8%).	65
B cells	Lower B1 cells (50% of B cells at birth), with higher IgM secretion. Lower CD40 expression.	77