Early loss of DP T cells in intestinal tissues in SIV infection. Dot plots comparing T-cell subsets from intestinal (jejunum and colon) tissues and peripheral blood of 2 normal, uninfected neonatal macaques (GK92 and GP52) to age-matched SIV_mac251-infected (GL48 and GP20) neonates. Plots were generated by gating on lymphocytes and then through CD3⁺ T cells. Note that a more dramatic loss of DP CD4⁺CD8⁺ T cells was detected in intestinal tissues in infected macaques very early in infection (as indicated by the arrows) compared with other tissues. The percentages of CD4⁺ and CD8⁺ cells are shown in each quadrant.