Disease Progression in Children With Perinatal Human Immunodeficiency Virus Correlates With Increased PD-1+ CD8 T Cells That Coexpress Multiple Immune Checkpoints.

Background: PD-1 marks exhausted T cells, with weak effector functions. Adults living with human immunodeficiency virus (HIV) have increased levels of PD-1+ CD8 T cells that correlate with HIV disease progression, yet little is known about the role of PD-1+ CD8 T cells in children with perinatal HIV.

Methods: We enrolled 76 Kenyan children with perinatal HIV and 43 children who were HIV unexposed and quantified PD-1 levels on CD8 T cells; their coexpression with immune checkpoints (ICs) 2B4, CD160, and TIM3; correlates with immune activation and HIV disease progression; and HIV-specific and -nonspecific proliferative responses.

HIV-Infected Children Have Elevated Levels of PD-1+ Memory CD4 T Cells With Low Proliferative Capacity and High Inflammatory Cytokine Effector Functions.

Background: During human immunodeficiency virus (HIV) disease, chronic immune activation leads to T-cell exhaustion. PD-1 identifies "exhausted" CD8 T cells with impaired HIV-specific effector functions, but its role on CD4 T cells and in HIV-infected children is poorly understood.

Methods: In a Kenyan cohort of vertically HIV-infected children, we measured PD-1+ CD4 T-cell frequencies and phenotype by flow cytometry and their correlation with HIV disease progression and immune activation.

HIV-Infected Children Have Lower Frequencies of CD8+ Mucosal-Associated Invariant T (MAIT) Cells that Correlate with Innate, Th17 and Th22 Cell Subsets.

Mucosal-associated invariant T cells (MAIT) are innate T cells restricted by major histocompatibility related molecule 1 (MR1) presenting riboflavin metabolite ligands derived from microbes. Specificity to riboflavin metabolites confers MAIT cells a broad array of host-protective activity against gram-negative and -positive bacteria, mycobacteria, and fungal pathogens. MAIT cells are present at low levels in the peripheral blood of neonates and gradually expand to relatively abundant levels during childhood.