Fig. 3.

Bulk and per-cell HIV-specific CD8⁺ T-cell cytotoxic responses of B*27/57^neg LTNP/EC exceeded those of progressors and were comparable to those of B*27/57^pos LTNP/EC. After 1 h co-incubation, CD8⁺ T-cell cytotoxic responses measured by (A) GrB target cell activity (circles) and (B) infected CD4⁺ T-cell elimination (ICE, diamonds) are shown for B*27/57^neg LTNP/EC (open symbols, n = 17), B*27/57^pos LTNP/EC (solid black symbols, n = 18) and viremic progressors (solid gray symbols, n = 18). Horizontal lines represent median values. Data are representative of three independent experiments. Comparisons were made using the Wilcoxon two-sample test. Only significant p values are shown. Per-cell cytotoxic capacity was assessed in B*27/57^neg LTNP/EC (red symbols), B*27/57^pos LTNP/EC (black open symbols) and viremic progressors (solid gray symbols) through comparisons of cytotoxicity curves, which were generated by plotting (C) GrB activity and ICE (D) values against the true E/T ratios based upon measurements of IFN-γ⁺ CD8⁺ T-cells and p24-expressing targets. Analysis of covariance was used to quantify the differences in GrB activity and ICE among the groups over the shared range of logged E/T ratios.