Expression of CD45RA, CD45RO, CD44, and CD95 markers by human T cells from infant thymus, cord or adult peripheral blood, lymph nodes, and spleen. Profiles are gated for live cells expressing CD4. Two populations of CD25^bright and CD25^int T cells are identified by the boxes, with the numbers giving the relative percentages in each population. Results are representative of 6 to 9 independent experiments.