Objectives: This study examined the homeostatic parameters possibly related to HIV-infected patients who, despite being under suppressive highly active antiretroviral therapy (HAART), show low-level CD4 T cell repopulation (LLR).
Methods: Twenty-one LLR individuals, 20 HIV-infected controls with satisfactory CD4 T cell repopulation (R) and 14 healthy subjects were studied. Markers related to activation, senescence and proliferation were analysed for both the CD4 and CD8 T cell subsets. Additionally, soluble CD14 (sCD14) and high-sensitivity C-reactive protein (hsCRP) were measured, and the CD34+ cells and the levels of interleukin-7 (IL-7) receptor were quantified.
Results: The frequency of naive CD4 T cells from LLR patients was significantly reduced, and these cells showed increased expression of markers for activation, senescence and proliferation as compared with naive CD4 T cells from R patients. Naive CD8 T cells were also reduced when compared with those from R patients, but did not exhibit an altered phenotype. Moreover, frequencies of effector memory T cells were higher in LLR than R patients. No differences between LLR and R patients were observed for sCD14 levels, CD34+ cells and the IL-7 receptor, although LLR patients showed a tendency toward increased levels of hsCRP >2 μg/mL.
Conclusions: Patients with low CD4 T cell restoration under suppressive HAART show significant alterations in T cell homeostasis that do not appear to be related to a reduction in haematopoietic progenitors. sCD14 levels were not specifically altered in these patients. Our results agree with our previously proposed model of premature immunosenescence in LLR patients and further describe homeostatic features associated with poor CD4 recovery.