Figure 3

CD4 and CCR5 mediated different signaling. (A) Purified tonsil CD4 T cells were incubated with soluble HIV gp120 protein (BaL, 10 μg/ml) in the absence or presence of VRC01 (20 μg/ml), sCD4 (20 μg/ml) or Maraviroc (1 μM) for 24 hours (n = 4). Frequency of CCR5+ cells was measured by flow cytometry. The statistical significance was analyzed. *P < 0.05, **P < 0.005, ***P < 0.0001 (Student’s t test). (B) Purified tonsil CD4 T cells were incubated with or without BaL-gp120 for 1 h on ice. Thereafter, cells were incubated at 37°C for 2 minutes to induce stimulation. (C) Purified tonsil CD4 T cells were untreated or pretreated with specific inhibitors (2μM) for Akt (LY294002), Erk (U0126) or p38 (SB203580) for 1 hour at 37°C before incubated with BaL gp120 (10 μg/ml) for 24 hours (n = 4). Frequency of CCR5+ cells was measured by flow cytometry. The statistical significance was analyzed. *P < 0.05, **P < 0.005, ***P < 0.0001 (Student’s t test). (D) A representative result of CCR5+ cells in tonsil CD4 T cells in different culture conditions as described above for 24 hours. (E) A proposed model based on our findings that Env-CD4 binding induced survival signals (Akt and Erk) that counteracted or directly inhibited the death signal (p38) generated upon Env binding to CCR5.