FIG. 7.

Functional properties of SIV-specific CD8⁺ T lymphocytes in sooty mangabeys. (A) Representative data of the ICS assay of PBMC stimulated with the SIV Env peptide pool in one naturally SIV-infected sooty mangabey. The four-color flow cytometric panels consisted of antibodies to CD3, CD8, and IFN-γ combined with either MIP-1β (left dot plot), TNF-α (middle dot plot), or IL-2 (right dot plot). Dot plots show gated CD3⁺ CD8⁺ T lymphocytes. The frequencies of SIV-specific IFN-γ-secreting, TNF-α-secreting, and MIP-1β-secreting CD8⁺ T lymphocytes were determined after subtraction of responses obtained with unstimulated (medium) PBMC. (B) Bar graph showing the proportion of responding SIV-specific CD8⁺ T lymphocytes exhibiting one or two functions in tubes containing IFN-γ combined with either MIP-1β, TNF-α, or IL-2. Means and SD of seven responses in six animals are shown. The open bars show the proportion of SIV-specific CD8⁺ T lymphocytes secreting IFN-γ alone in the respective tubes, the closed bars show the double-positive population, and the hatched bars show the proportion secreting MIP-1β, TNF-α, or IL-2 in the absence of IFN-γ.