Polychromatic (8 color) flow cytometry demonstrating that central memory (CD95⁺CD28⁺) CD4⁺ T cells from different tissues have different expression patterns of activation markers (CD25, CD69) as well as CCR5 and CD45RA. Plots were gated through lymphocytes and then through CD3⁺CD4⁺ T cells from tissues from an uninfected neonate (GA98, 14 days). Note that central memory (CD95⁺CD28⁺) CD4⁺ T cells from the intestine have much higher CD69 and CCR5 expression than those from the spleen or blood.