Memory phenotype CD8⁺T cells are more abundant in early life and express different surface markers and transcription factors. (A) Surface expression of CD44 and CD122 by splenic CD8⁺ T cells from uninfected neonatal and adult gBT-I. (B) Statistical analysis of the percentages of MP cells from neonatal and adult gBT-I mice. (C) Comparison of various surface markers and transcription factors expressed in TN and MP cells from uninfected neonatal (line) or adult (shaded) gBT-I mice. Data are representative of at least 3 experiments. Significance was determined by Student t test (****P < .0001).