SIV-specific CD8⁺ T cell cytotoxicity measured by granzyme B delivery or Infected CD4 Elimination (ICE).

<p><b>A.</b> The top panels show granzyme B (GrB) target cell activity representative of a “high responder”. The bottom panels show GrB target cell activity representative of a “low responder”. Values indicate percentages of targets with increased fluorescence due to GrB substrate cleavage. Background GrB target cell activity measured in response to uninfected targets (left column) was subtracted from responses measured against infected targets (right column) to determine net GrB target cell activity (red values). <b>B.</b> ICE values calculated based on p27 expression (sum of the upper quadrants) as described in the Methods, are shown in red for the same “high responder” (78.8%, top row) and “low responder” (22.3%, bottom row) as shown in A. Quadrant values indicate percentages of gated targets. In all experiments, CD4⁺ T cell lines were used as targets. CD8⁺ T cells that had been stimulated with SIV-infected targets for 6 days were used as effectors. GrB target cell activity and ICE were calculated after 1 hour of incubation of effectors and plated at an E∶T ratio of 25∶1.