Fig. 3.
Most RhCMV vector-elicited CD8+ T cell responses are inhibited by MHC-II blockade. (A) PBMC from a representative strain 68-1 RhCMV/gag-vaccinated RM (of 8 RM similarly analyzed RM, see fig. S5) were stimulated with the designated SIVgag core epitopes (Type 1 vs. Type 2) in the presence of irrelevant isotype control mAbs (IgG1 − clone X40 + IgG2a − clone X39; 10μg each), an anti-MHC-I mAb (W6-32; 10μg), an anti-MHC-II mAb (G46-6; 10μg), or the CLIP peptide (MHC-II-associated invariant chain, amino acids 89-100; 2μg). A typical CD4 vs. CD8 expression profile, showing events gated on CD3+ small lymphocytes, is illustrated on the left, with the CD8 gate used to analyze the CD8+ T cell responses indicated. The IFN-γ vs. TNF-α profiles (right panels) include only events collected through these gates, and thus reflect CD8hi/CD4negative T cells. (B,C) All the SIVgag 15mer peptide responses shown in Fig. 2A were subjected to MHC-I (mAb W6-32) vs. MHC-II (mAb G46-6) blockade and classified as being specifically inhibited (blocked) by anti-MHC-I vs. anti-MHC-II mAbs, or indeterminate. (B) For each RM, the average number of peptide-specific responses in each category are shown, classified by vaccine type. (C) The sensitivity of each SIVgag peptide response in 14 strain 68-1 RhCMV/gag-vaccinated RM [*BAC-derived RhCMV/gag; **non-BAC-derived RhCMV/gag(L)] to blockade by anti-MHC-I (red boxes) vs. anti-MHC-II (blue boxes) mAbs is shown (open boxes indicate indeterminate), with the minimal number of independent epitopes in the MHC-I- and MHC-II-associated categories designated at right (note: the total number of independent epitopes increased in some RM from that listed in Fig. 2A due to increased resolution afforded by the MHC blocking data).