title: 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 = 99) or HIV-1-seronegative (n = 32) subjects, and correlating these results with the level of circulating CD4(+) and CD8(+) 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(+) T cell count (P = 0.02) and a higher percentage and absolute number of circulating naive (CD45RA+CD62L+) CD4(+) T cells (P < 0.04). The prevalence of an abundant thymus was especially high in younger HIV-1-seropositive adults (</= 39 yr) with CD4 counts in the range 300-500 cells/microl and in older subjects (> 40 yr) regardless of CD4 count (P = 0.03). These studies suggest that the thymus is functional in some but not all adults with HIV-1 disease.
authors.affiliation: The Gladstone Institute of Virology and Immunology, University of California, San Francisco, San Francisco, California 94141-9100, USA. Mike_McCune.givi@quickmail.ucsf.edu
authors.forename: J M
authors.initials: JM
authors.lastname: McCune
authors.forename: R
authors.initials: R
authors.lastname: Loftus
authors.forename: D K
authors.initials: DK
authors.lastname: Schmidt
authors.forename: P
authors.initials: P
authors.lastname: Carroll
authors.forename: D
authors.initials: D
authors.lastname: Webster
authors.forename: L B
authors.initials: LB
authors.lastname: Swor-Yim
authors.forename: I R
authors.initials: IR
authors.lastname: Francis
authors.forename: B H
authors.initials: BH
authors.lastname: Gross
authors.forename: R M
authors.initials: RM
authors.lastname: Grant
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology*; D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D003430:Cross-Sectional Studies; D015497:HIV-1; D006801:Humans; D008875:Middle Aged; D013950:Thymus Gland / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed