HIV-Specific CD8+ T Cells Exhibit Reduced and Differentially Regulated Cytolytic Activity in Lymphoid Tissue

Elimination of lymphoid tissue reservoirs is a key component of HIV eradication strategies. CD8(+) T cells play a critical role in control of HIV, but their functional attributes in lymph nodes (LNs) remain unclear. Here, we show that memory, follicular CXCR5(+), and HIV-specific CD8(+) T cells from LNs do not manifest the properties of cytolytic CD8(+) T cells. While the frequency of follicular CXCR5(+) CD8(+) T cells was strongly inversely associated with peripheral viremia, this association was not dependent on cytolytic CXCR5(+) CD8(+) T cells. Moreover, the poor cytolytic activity of LN CD8(+) T cells was linked to a compartmentalized dissociation between effector programming and the transcription factor T-bet. In line with this, activation of LN CD8(+) T cells only partially induced the acquisition of cytolytic functions relative to peripheral blood CD8(+) T cells. These results suggest that a state of immune privilege against CD8(+) T cell-mediated cytolysis exists in lymphoid tissue, potentially facilitating the persistence of HIV.