Immune activation despite preserved CD4 T cells in perinatally HIV-infected children and adolescents.

Background: HIV disease progresses more rapidly in children than adults with mortality rates exceeding 50% by 2 years of age without antiretroviral therapy (ART) in sub-Saharan Africa. Recent World Health Organization (WHO) guidelines recommend universal treatment for all living persons with HIV, yet there is limited supporting evidence in pediatric populations. The objective of this study was to determine whether CD4 cell counts reflect immunological markers associated with disease progression in ART naïve perinatally-infected HIV+ children and adolescents and their response to ART.

Methods: PBMC and plasma samples were collected from 71 HIV negative and 132 HIV+ children (65 ART naïve and 67 on ART) between ages 1-19 years from Mombasa, Kenya. Untreated HIV+ subjects were sub-categorized by high or low CD4 T cell counts. Immune activation markers CD38, HLA-DR and Ki67 were analyzed by flow cytometry. Plasma soluble CD14 (sCD14) was quantified by ELISA.

Results: HIV-infected children and adolescents with preserved CD4 cell counts had depleted CD4 percentages and CD4:CD8 ratios, and high immune activation levels. ART initiation rapidly and persistently reversed T cell activation, but failed to normalize CD4:CD8 ratios and plasma sCD14 levels.

Conclusions: Diminished CD4 percentages and CD4:CD8 ratios along with profound immune activation occur independent of CD4 cell count thresholds in ART naïve HIV+ children and adolescents. Immediate ART initiation, as recommended in the most recent WHO guidelines may protect them from pathologic sequelae associated with persistent inflammation.