Decreased maturation of DCs cocultured with T cells activated in presence of AT-2 HIV. Purified CD4⁺ T cells were left unstimulated (unstim) or stimulated with anti-CD3/CD28 beads, either without treatment (untreated) or in the presence of control microvesicles (vesicle) or AT-2 HIV_MN (AT-2 HIV). After 24 hours, T cells were mixed with autologous monocyte-derived DCs at a ratio of 5:1. Similar percentages of dead T cells (∼ 10%) were observed in the different cultures before coculture (results not shown). (A) Inhibition of DC activation marker expression in one representative subject. Expression markers were determined on DCs, gated on forward-scatter and CD1a expression. Open histograms represent the staining by the isotype-matched control Ab. Closed histograms represent the staining by the Ab of interest. Numbers in the graph represent the MFI for each condition. (B) Inhibition of DC activation marker expression in 7 subjects. Results are shown as the mean (± SE) MFI obtained in 7 individual subjects. (C) Inhibition of production of immunoregulatory cytokines. Levels of IL-12 p40 and IL-10 in 24-hour coculture supernatants were determined by ELISA. Results are shown as the mean (± SE) levels measured in 7 individual subjects. (B-C) ^*Significant inhibition (P < .05, paired t test) between untreated and AT-2 HIV exposed; ^#significant inhibition (P < .05, paired t test) between vesicle- and AT-2 HIV-exposed.