Selective decrease in the proportion of CD44^high CD8 T cells, but not other lymphoid populations, in c-myc^+/– mice. (A) Splenocytes from wt and c-myc⁺/– littermates were analyzed for expression of TCRαβ, TCRγδ, CD19, NK1.1, CD4, and CD8. The numbers shown represent the percentage of cells within each quadrant. The results shown are representative of 3 experiments and 5 mice per group were analyzed in each experiment. (B) Naive (N) and memory-phenotype (MP) CD8 and CD4 T cells were defined by expression of CD8, CD62L, CD122, and CD44 (top panels) or CD4, CD62L, and CD44 (bottom panels). Bar graphs indicate the mean percentages ± SD of N and MP cells within CD8 or CD4 populations from wt and c-myc⁺/– littermates. The results shown are representative of more than 5 experiments. **P < .01. (C) c-myc mRNA levels were determined by real-time PCR in sorted naive CD44^low and memory-phenotype CD44^high CD8 and CD4 T cells from wt and c-myc⁺/– littermates. Values for c-myc were normalized to TBP values and presented in arbitrary units. Mean ± SD of triplicate samples is indicated.