FIG. 3.

IVK mediated by CD8⁺ cells. (A) Depletion of CD8⁺ T cells (○) following administration of a CD8 depleting monoclonal antibody over 7 days (arrows) in immunized and SHIV_mn229-challenged macaque H21 led to a brisk rise in SHIV viremia (▵). Repletion of CD8⁺ T cells correlated temporally with recontrol of viremia, in association with strong T-cell immunity as measured by ICS (bars) to Gag (CD4⁺ [□] and CD8⁺ [▪]) and Pol (CD4⁺ [░⃞] and CD8⁺ [hatched]). No Pol responses were assayed between weeks 18 and 33 post-SHIV challenge, and no Gag or Pol responses were assayed at week 8 post-SHIV challenge and between days 10 and 19 post-CD8⁺-T-cell depletion. (B) Flow cytometric analysis of IVK of infused PBMC pulsed with SIV peptides: Pol (SNARF, red); Gag (CFSE^lo, green), and DMSO (CFSE^hi, green; control population) was performed on macaque H21 on day 9 of CD8 depletion. A similarly immunized and SHIV_mn229-challenged but non-CD8-depleted macaque, H20, was assayed concurrently. Cell numbers are expressed as values relative to those of the control population.