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Open Access Research article

High T-cell immune activation and immune exhaustion among individuals with suboptimal CD4 recovery after 4 years of antiretroviral therapy in an African cohort

Damalie Nakanjako12*, Isaac Ssewanyana3, Harriet Mayanja-Kizza1, Agnes Kiragga2, Robert Colebunders56, Yukari C Manabe2, Rose Nabatanzi3, Moses R Kamya1 and Huyen Cao4

Author Affiliations

1 Department of Medicine, Makerere University School of Medicine, Kampala, Uganda

2 Infectious Diseases Institute, Makerere University School of Medicine, Kampala, Uganda

3 Joint Clinical Research Center, Kampala, Uganda

4 California Department of Public Health, Richmond, California 94804, USA

5 Institute of Tropical Medicine, Department of Clinical sciences, HIV/STD Unit, Antwerp, Belgium

6 Department of Epidemiology and Social Sciences, University of Antwerp, Antwerp, Belgium

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BMC Infectious Diseases 2011, 11:43  doi:10.1186/1471-2334-11-43

Published: 8 February 2011

Abstract

Background

Antiretroviral therapy (ART) partially corrects immune dysfunction associated with HIV infection. The levels of T-cell immune activation and exhaustion after long-term, suppressive ART and their correlation with CD4 T-cell count reconstitution among ART-treated patients in African cohorts have not been extensively evaluated.

Methods

T-cell activation (CD38+HLA-DR+) and immune exhaustion (PD-1+) were measured in a prospective cohort of patients initiated on ART; 128 patient samples were evaluated and subcategorized by CD4 reconstitution after long-term suppressive treatment: Suboptimal [median CD4 count increase 129 (-43-199) cells/μl], N = 34 ], optimal [282 (200-415) cells/μl, N = 64] and super-optimal [528 (416-878) cells/μl, N = 30].

Results

Both CD4+ and CD8 T-cell activation was significantly higher among suboptimal CD4 T-cell responders compared to super-optimal responders. In a multivariate model, CD4+CD38+HLADR+ T-cells were associated with suboptimal CD4 reconstitution [AOR, 5.7 (95% CI, 1.4-23, P = 0.014)]. T-cell exhaustion (CD4+PD1+ and CD8+PD1+) was higher among suboptimal relative to optimal (P < 0.001) and super-optimal responders (P < 0.001). T-cell exhaustion was significantly associated with suboptimal responders [AOR, 1.5 (95%CI, 1.1-2.1), P = 0.022].

Conclusion

T-cell activation and exhaustion persist among HIV-infected patients despite long-term, sustained HIV-RNA viral suppression. These immune abnormalities were associated with suboptimal CD4 reconstitution and their regulation may modify immune recovery among suboptimal responders to ART.