Increased apoptosis of monocytes and DCs during primary SIV infection.

<p>PBMC from healthy (<b>SIV⁻</b>) and SIV-infected RM at day 14 (<b>SIV⁺</b>) were incubated overnight in the absence or presence of death ligands. (<b>A</b>) The percentages of apoptotic CD4⁺ T cells were analyzed by flow cytometry using FITC-labeled Annexin V. (<b>B</b>) Gating strategy to analyze apoptotic HLA-DR⁺ and CD14⁺ cells. Cells were first analyzed on HLA-DR <i>versus</i> SSC (gate R1) and HLA-DR <i>versus</i> Lin+(CD3⁺CD14⁺CD20⁺) cells (gate R2), or CD14 <i>versus</i> Lin+(CD3⁺CD20⁺) cells (gate R3) (<b>C</b>) The percentages of apoptotic HLA-DR⁺Lin⁻ (CD3⁻CD14⁻CD20⁻) cells was determined by flow cytometry using FITC-labeled Annexin V gated on R1 and R2; (<b>D</b>) Percentage of apoptotic CD4⁺ and HLA-DR⁺Lin⁻ cells. Values shown are means ± SEM (n = 4 for SIV⁻ and SIV⁺); Significantly different compared to medium controls (*, p<0.05). (<b>E</b>) Percentage of apoptotic monocytes (MØ) and DCs at days 0, 11, 14 and 60; values are means ± SEM (n = 6); Significantly different from day 0 (*, p<0.05). (<b>F</b>) PBMC from healthy and SIV-infected AGM at day 14. The percentages of apoptotic CD4⁺ T cells and HLA-DR⁺CD3⁻CD20⁻ cells were analyzed by flow cytometry using FITC-labeled Annexin V. (<b>G</b>) Quantitation of FasL in the sera of SIV-infected RMs and AGM at different time points post-infection. Statistical significant differences as compared to day 0 are indicated by an asterisk. (<b>H</b>) Preventive effect of death receptor antagonists. PBMC from SIV-infected RMs (day 14) were incubated overnight with antagonists of death receptors: TRAIL-R1, TRAIL-R2, Fas-Fc and TNF-R1 (10 µg/ml). Apoptosis of monocytes and DCs was quantified using FITC-Annexin-V. Preventive effect was calculated as follows: ((% of MØ/DC apoptosis - % of MØ/DC apoptosis in the presence of decoy receptors)/(% of MØ/DC apoptosis)) X 100. Values are means ± SEM (n = 5); Significantly different from samples incubated with medium alone (*, p<0.05).