Evidence of thymic function in heavily antiretroviral-treated human immunodeficiency virus type 1-infected adults with long-term virologic treatment failure

Thymic function was evaluated in 32 heavily antiretroviral-treated human immunodeficiency virus type 1 (HIV-1)-infected adults with long-term virologic treatment failure by measuring thymic volume, by determining the absolute number of naive T cell phenotypes, and by determining the number of cells carrying T cell receptor excision circles (TRECs). There was a significant inverse correlation between age and thymic volume (r = -0.415; P = .018), and there was a significant direct correlation between thymic volume and total naive T cell counts (r = 0.529 P = .002), naive CD4(+) cell counts (r = 0.437 P = .012), naive CD8(+) cell counts (r = 0.467; P = .007), and TREC levels (r = 0.391; P = .027). In conclusion, this study found clear evidence that the thymus of heavily antiretroviral-treated HIV-1-infected adults with long-term virologic treatment failure is actively engaged in thymopoiesis, which generates new naive T cells for the peripheral lymphocyte pool.