Effector memory CD8+ and CD4+ T cells in naïve and p52- immunized mice. For each analysed organ, cell populations were defined as either CD8+ or CD4+ T cells, and subpopulations of effector memory cells within those populations were defined as CD44highCD62Llow. (A) Flow cytometry analysis of CD8+CD44highCD62Llow memory T cells in the liver of naïve (left panels) or immunized (Imm, right panels) mice 10 days after immunization with p52- sporozoites. Although the levels of CD8+ T cells are similar in both naïve and Imm mice (8.9% versus 12.4%, upper panels), the percentage of CD8+ effector memory cells is much higher in Imm than in naïve mice (61.3% versus 19.8%, lower panels). Values refer to percentage of cells in the respective quadrant. (B) Relative proportion (fold increase) of CD8+ effector memory T cells in naïve and immunized mice (n = 3 per group) in liver (Lv), spleen (Sp) and lymph nodes (LN) at different time points after immunization (A.I.). Effector memory CD8+ T cells were quantified as shown in (A) and results are displayed as fold increase in immunized mice over naive mice. (C) Relative proportion of CD4+CD44highCD62Llow (effector) memory T cells in the same immunized and naïve mice as shown in (B). These cells were quantified as described in (B) from mice at 10 days after immunization. FACS analyses were performed on pooled cells from three animals within the same group, and 100,000 to 200,000 events per each phenotype studied were analysed.