Uncovering the Hidden Players: Double-negative T Cells in Pediatric HIV and Their Impact on Disease Progression

Background: Immune reconstitution in pediatric HIV infection under antiretroviral therapy (ART) is monitored by CD4 + T-cell counts and the CD4/CD8 ratio, whereas the role of double-negative T cells (DNTs; CD3 + CD4 − CD8 − ) is poorly defined. We aimed to characterize CD4 + /CD8 + T-cell dynamics and age-dependent DNT patterns. Methods: In this retrospective cohort, 30 children were followed for 12 months after ART initiation. Flow cytometry was used to measure CD3 + , CD4 + , CD8 + and DNT subsets and the CD4/CD8 ratio; demographic, clinical and coinfection data were abstracted from medical records. Results: The cohort comprised 30 children (20 boys, 10 girls; mean age 10.4 years). ART increased CD4 + and decreased CD8 + T-cell percentages, with the CD4/CD8 ratio rising from 0.73 to 1.09 and normalizing (≥1.0) in 63.3% of children. Baseline DNT levels were elevated (mean 7.0%) but declined significantly, normalizing (<5%) in adolescents, whereas children 0–5 years maintained higher residual levels. Higher DNT percentages correlated with lower CD4 + counts and an inverted CD4/CD8 ratio. Cytomegalovirus and Epstein-Barr virus viremia were common; in 3 children with dual cytomegalovirus/Epstein-Barr virus viremia, baseline CD4 + percentages were lower and DNT percentages higher, and 1 had celiac disease, suggesting that dual viremia on a background of immune-mediated disease may delay immune reconstitution. DNT% reduction showed a trend toward greater decrease with integrase inhibitor–based regimens. Conclusions: In pediatric HIV infection, CD4/CD8 ratio normalization and DNT decline depict a more nuanced immune reconstitution than CD4 + recovery alone. Age-dependent DNT trajectories support incorporating DNT monitoring as a complementary biomarker in pediatric ART management.