CXCR4 and CCR5 molecules per cell on CD4^dimCD8^bright T cells. Quantibright beads were used to quantify the number of CXCR4 and CCR5 molecules on (A) SEB- and (B) anti-CD3/CD28–stimulated CD8⁺ T cells to generate CD4^dimCD8^bright (▪) and CD8⁺CD4^– (□) phenotypes. In addition, SEB- and anti-CD3/CD28–stimulated CD4⁺ T cells from PBMC cultures (▦) were also quantitated for CXCR4 and CCR5 expression. Data represent the mean number of molecules per cell of at least 8 donors ± SD. Asterisk denotes statistical significance (P = .002) between SEB-treated CD8⁺CD4^– and CD4^dimCD8^bright, as determined by the Wilcoxon signed rank test. (C) A representative histogram of the data pertaining to CD4^dimCD8^bright T cells is shown, with CXCR4 and CCR5 MI referring to the geo mean fluorescent intensity on CD4⁺ and CD8⁺CD4^– cells shown in the data below the respective histogram.