FIGURE 5.

Levels of P-TEFb must be increased before HDACis can reactivate HIV in primary resting CD4⁺ T cells. A, levels of P-TEFb are low in primary CD4⁺ T cells and increase following PKC activation. CD4⁺ T cells were isolated and expanded from anonymous healthy donors (see “Experimental Procedures”). They were incubated for the indicated periods of time with bryostatin 1, PHA, or SAHA. Levels of CycT1 and CDK9 were determined by Western blotting. Levels of actin were measured as loading controls. B, increased levels of P-TEFb are required before HDACis can reactivate HIV in primary CD4⁺ T cells. Isolated CD4⁺ T cells were treated as in A. Resting cells were treated with bryostatin 1, SAHA, or combinations thereof for 24 h at the indicated concentrations. Luciferase activity was determined in cell lysates, normalized to total protein content, and calculated as -fold activation over the DMSO control (bar 1, set to 1). Experiments with two different lots of peripheral blood mononuclear cells are presented. Error bars represent S.E. of mean of experiments performed in triplicate.