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Summary B cell follicles (BCFs) in the lymph node are a major sanctuary for HIV reservoirs. Immune regulatory mechanisms hindering cytolytic CD8+ responses at these sites are poorly characterized, likely enabling HIV persistence. Spatial transcriptomics and high-dimensional histocytometry were used to define CD8+ T cell function and immune regulation in lymph node (LN) follicles of people living with HIV (PLWH), at various stages of antiretroviral therapy (ART) treatment. Histocytometry demonstrated that CD8+ T cells infiltrating BCFs mostly lacked granzyme B expression, coinciding with reduced chromatin access at cytolytic gene loci in dissociated lymph node cells. Spatial transcriptomics confirmed the immune regulatory microenvironment of HIV-infected BCFs, particularly exhibiting upregulation of HLA-E. Additional fluorescence-activated cell sorting (FACS) analysis identified a subset of LN CD8+ T cells expressing the NKG2A-interacting partner of HLA-E, with reduced granzyme B expression. These findings suggest that regulation of follicular CD8+ T cells at the HLA-E-NKG2A axis may be a key mechanism for HIV immune evasion.
Papadopoulos et al. (Fri,) studied this question.