Fig. 3.

Effects of HIV infection of CD8⁺ T cells. (a) HIV-1 replication in costimulated CD8⁺ T cells and peripheral blood leukocytes (PBL). Costimulated CD8⁺ T cells purified from PBL (Left) or whole PBL (Right) were infected with R5-tropic HIV-1_BAL (▪), HIV-1_ADA-M (♦), R5/X4 dual tropic HIV-1_89.6 (▴), or X4-tropic HIV-1_IIIB (•) and p24gag production measured daily by ELISA. (b) HIV down-regulation of CD4 in CD8⁺ T cells. CD4 expression on costimulated CD8⁺ T cells from uninfected culture (Left), HIV-1_NL4–3-infected cultures (Center), and HIV_NL4–3 p24⁺ cells (Right). Percentages of CD4⁺ cells are above the indicated gate, and mean fluorescent intensities (MFI) of CD4 expression are below the gate. (c) HIV perturbation of the IFN-γ response. IFN-γ expression, measured by ELISPOT with or without ligation of CD4 by XL-CD4 for 3 days (left) or 6 days (right) after costimulation and mock treatment or infection with HIV-1_NL4–3. Data are expressed as the number of IFN-γ⁺ cells per million. (d) Perturbation of FasL expression by HIV infection of CD8⁺ T cells. CD8 versus FasL expression of either mock-treated or HIV-1_NL4–3-infected cells 3 days after infection, 6 h after treatment with either medium alone or with XL-CD4 mAb, as indicated. Percentages of CD8⁺FasL⁺ cells are indicated. (e) Impairment of CD8⁺ T cell lytic function by HIV. The percent lysis of allogeneic target cells at the specified effector/target cell ratios are indicated with mock-treated (▪) and HIV-infected (♦) cells.