Figure 2.

Activation of caspase-3 and caspase-6 by HIV and SIV envelopes. Flow cytometric analyses of PBMCs treated with various recombinant envelopes or the anti-Fas mAb CH11, in the presence of a fluorogenic tetrapeptide substrate for caspase-3 (DEVD-Rho; A and B), or caspase-6 (VEID-Rho; C) are shown. In the histograms, mcf is displayed on the x axis and total cell counts on the y axis; cells were gated on the CD3⁺ population. The anti-Fas mAb CH11 was employed as a positive control. The marker boundary (M1) was set to exclude background staining in the untreated cells; the percentage of cells with mcf values above the marker boundary is indicated in each histogram. (B and C) mcf values over background are presented as in A.