High prevalence of thymic tissue in adults with human immunodeficiency virus-1 infection.

Abstract

The thymus in adults infected with the HIV-1 is generally thought to be inactive, both because of age-related involution and viral destruction. We have revisited the question of thymic function in adults, using chest-computed tomography (CT) to measure thymic tissue in HIV-1-seropositive ( n ϭ 99) or HIV-1-seronegative ( n ϭ 32) subjects, and correlating these results with the level of circulating CD4 ϩ and CD8 ϩ T cells that are phenotypically described as naive thymic emigrants. Abundant thymic tissue was detectable in many (47/99) HIV-1-seropositive adults, aged 20-59. Independent of age, radiographic demonstration of thymic tissue was significantly associated with both a higher CD4 ϩ T cell count ( P ϭ 0.02) and a higher percentage and absolute number of circulating naive (CD45RA ϩ CD62L ϩ ) CD4 ϩ T cells ( P Ͻ 0.04). The prevalence of an abundant thymus was especially high in younger HIV-1-seropositive adults ( Յ 39 yr) with CD4 counts in the range 300-500 cells/ l and in older subjects ( Ͼ 40 yr) regardless of CD4 count ( P ϭ 0.03). These studies suggest that the thymus is functional in some but not all adults with HIV-1 disease. ( J. Clin. Invest. 1998.

Changes in thymus volume in adult HIV-infected patients under HAART: correlation with the T-cell repopulation

“…Using this approach, McCunne et al . [10] found abundant thymic tissue measured by a CT slice in half of the untreated adult HIV-1 infected patients over 39 years old. This same group observed that the evolution of naïve T-cells during the follow up was associated with larger thymuses at the end of the treatment period [11].…”

Normal Telomere Lengths in Naive and Memory CD4+ T Cells in HIV Type 1 Infection: A Mathematical Interpretation

“…This is the "limited renewal" scenario. 8,10,11,16,35,44 The two scenarios differ in the mechanism for disease progression, and in the relevance of therapies aiming at immune reconstitution. In the limited renewal scenario disease progression is due to insufficient production in the CD4 1 T cell com partment, whereas in the proliferative exhaustion scenario it is the highly stressed homeostatic response that causes the regenerative capacity to ultimately, and irreversibly, burn out.…”

Thymopoiesis in elderly human is associated with systemic inflammatory status

“…The interest in human thymic function in the elderly has increased after studies showed that (1) the adult thymus of HIV-infected patients without treatment (McCune et al 1998) or under highly active antiretroviral therapy (HAART) (Franco et al 2002;De la Rosa and Leal 2003) maintained or even improved its function, actively contributing to the CD4 lymphocyte repopulation; (2) adult thymopoiesis can be increased with growth hormone administration (Goldberg et al 2007) or pharmacological androgenic blockade (Sutherland et al 2005;Goldberg et al 2007b). Therefore, the capacity of effectively reversing, at least partially, the thymic atrophy opens up new perspectives in order to delay the immunosenescence process.…”