Thymic Function during 12 Months of Highly Active Antiretroviral Therapy in Thai HIV-Infected Patients with Normal and Slow Immune Recovery.

The aim of this study was to determine and compare thymic output during 12 months of highly active antiretroviral therapy (HAART) in HIV-infected patients with different types of immune recovery. In total, 18 Thai HIV-infected patients with normal immune recovery (NR) and 13 Thai HIV-infected patients with slow immune recovery (SR) were enrolled. T-cell receptor rearrangement excision circle (TREC) levels in peripheral blood mononuclear cells (PBMCs) and CD4(+) T cells were quantified at baseline, and after 6 and 12 months of HAART. CD4(+) T-cell counts in NR patients were significantly higher than those in SR patients after 6 and 12 months of HAART. However, the median TREC levels in PBMCs and CD4(+) T cells in both groups were comparable. Moreover, TREC levels showed similar trends in PBMCs and CD4(+) T cells in both groups during 12 months of HAART. Only patients with SR had significant increases in median TREC levels in PBMCs and CD4(+) T-cells during the first 6 months of HAART. No correlations were found between CD4(+) T-cell count and TREC levels in PBMCs and CD4(+) T cells. These results imply that the increase in CD4(+) T-cell count in SR patients after 12 months of HAART is likely attributable to thymic output and other sources.