Patterns and cofactors of polyfunctional mycobacteria-specific T cell response restoration following 6-month antiretroviral treatment in children living with HIV.

Background: Despite immune restoration after initiation of antiretroviral treatment (ART), the risk of tuberculosis (TB) persists in children living with HIV (CLHIV). We determined patterns of immune restoration of mycobacteria-specific T cells following ART in CLHIV.

Methods: CD4 and CD8 T cell activation and memory phenotype and functional profiles before and 6 months after ART were evaluated in peripheral blood mononuclear cells (PBMCs) from CLHIV enrolled in the PUSH study (NCT02063880) in Nairobi, Kenya. T cell expression of cytokines and activation induced markers (AIM) were measured following stimulation of PBMCs with a pool of 300 peptides from TB (MTB300) or staphylococcal enterotoxin B (SEB).

Results: Among 47 CLHIV of median age 1.5 years, SEB-induced Th1 cytokine+ and AIM+ CD4 cell frequencies increased significantly after 6 months ART. Although MTB300-specific CD4 and CD8 cell frequency did not increase after ART, polyfunctional capacity of MTB300-specific CD4 cells expressing combinations of Th1 cytokines with CD40L increased significantly after ART. Baseline age, immune activation, and effector memory CD4 levels were associated with less restoration of MTB300-specific polyfunctional CD4 cells, whereas CD4% and levels of naïve CD4 cells following ART were associated with improved MTB300-specific polyfunctional capacity.

Conclusions: Despite increases in Th1 cytokine production, deficits in mycobacteria-specific CD4 cells persisted 6 months after ART, with higher deficits in older CLHIV with more immunosuppression, higher immune activation, and lower proportion of naïve CD4 cells. These findings may explain persistent TB risk during early ART among CLHIV and identify those at highest risk.