FIG. 6.

T-cell proliferation is restored in the presence of ddI and CD95 decoy receptor. CD4⁺ T cells were incubated with HIV-1_LAI and purified as described for Fig. 5B. Cells were incubated in the absence (open bars) or presence (solid bars) of 5 μM ddI added at day 0 and day 2. CD4⁺ T cells were further stimulated in the absence (Med) or presence of CD3 MAb (1 μg/ml) or CD3 with CD28 MAbs (CD3 CD28) (1 μg/ml each). At day 3, T-cell proliferation (A), T-cell counts (B), and p24 antigen production (C) were assessed. (A) T-cell proliferation was determined by [³H]thymidine (TdR) incorporation. Results are the means of three independent experiments (means ± standard deviations). (B) T-cell counts were assessed by light microscopy. Results are the means of three independent experiments (means ± standard deviations). (C) Enzyme-linked immunosorbent assay specific for p24 antigen was used to assess viral production. Results are the means of three independent experiments (means ± standard deviations). Statistical significance was assessed by Student's t test (∗, P < 0.05; ns, no significant statistical difference). (D) PBMC were incubated for 2 h in the absence (open bars) or presence (filled bars) of HIV-1_LAI (at an MOI of 0.01) and then washed and further incubated in medium alone (None) or in the presence of ddI for 4 days. CD4⁺ T cells then were purified, by negative selection, and cultured for 18 h inthe presence of either CD3 MAb (1 μg/ml) or CD3 and CD28 MAbs (1 μg/ml each). CD4⁺ T cells treated with ddI were also incubated in the presence of a soluble CD95 decoy receptor (ddI/CD95-Fc) (10 μg/ml). T-cell counts were assessed by light microscopy at day 4. Results are the means of two independent experiments (means ± standard deviations).