FIG. 3.

Results for in vivo depletion of CD8⁺ cells (doses indicated by small open arrows) and heterologous (SIVmac239; 100 MID₅₀ intravenously) virus rechallenge (large open arrow) in animal Rh 120. (A) Plasma viral load (triangles) and viral genotype (bars; SIVsmE660 [grey] or SIVmac239 [white]), based on characterization of at least 20 independent clones derived from RT-PCR-amplified plasma viral RNA for each indicated time point. (B) Absolute CD3⁺ CD4⁺ cell counts per microliter of of peripheral blood (circles) and SIV-specific proliferative responses (diamonds). (C) Absolute CD3⁺ CD8⁺ cell counts per microliter of peripheral blood (circles), SIV-specific CD8⁺ cells/10⁵ total CD3⁺ CD8⁺ cells (diamonds), and SIV-inducible MIP-1β secretion (grey bars). LNMC from a biopsy specimen obtained after 2 of 3 doses of anti-CD8 MAb showed 15% residual CD3⁺ CD8⁺ cells, compared to 4% in matched PBMC. IFN-γ, gamma interferon.