title: Impact of thymectomy on the peripheral T cell pool in rhesus macaques before and after infection with simian immunodeficiency virus.
abstract: The goal of this study was to define, by surgical removal of the thymus in juvenile rhesus macaques, the role of the thymus in peripheral T cell homeostasis and to assess the significance of thymic output in SIV infection. By monitoring the changes in phenotypic T cell markers as well as in the numbers of TCR excisional circles--a recently described marker for recent thymic emigrants--following thymectomy, we present evidence that surgical thymectomy in juvenile macaques results in a faster decay of peripheral CD4(+) cells, but does not cause a substantial shift in CD45RA(+) and CD45RA(-) populations. We were able to measure a thymic output of 0.32% and 0.21% per day of CD4(+) and CD8(+) cells, respectively. No compensatory extra-thymic source was detected in lymphoid tissues, although there was a small compensatory increase in T cell proliferation in the peripheral T cell pool. After SIV infection, thymectomized animals did not have higher viral loads, greater T cell decay, or faster disease progression. We therefore conclude that peripheral destructive processes, rather than a loss of thymic output, appear to be the main causes of T cell depletion in SIV infection.
authors.affiliation: Aaron Diamond AIDS Research Center, The Rockefeller University, New York, NY 10016, USA.
authors.forename: Sarah Tuttleton
authors.initials: ST
authors.lastname: Arron
authors.forename: Ruy M
authors.initials: RM
authors.lastname: Ribeiro
authors.forename: Agegnehu
authors.initials: A
authors.lastname: Gettie
authors.forename: Rudolph
authors.initials: R
authors.lastname: Bohm
authors.forename: James
authors.initials: J
authors.lastname: Blanchard
authors.forename: Jian
authors.initials: J
authors.lastname: Yu
authors.forename: Alan S
authors.initials: AS
authors.lastname: Perelson
authors.forename: David D
authors.initials: DD
authors.lastname: Ho
authors.forename: Linqi
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics / Q000378:metabolism; D008253:Macaca mulatta; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D016097:Simian Acquired Immunodeficiency Syndrome / Q000209:etiology / Q000235:genetics / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013934:Thymectomy; D013950:Thymus Gland / Q000276:immunology*
chemical_list: D011948:Receptors, Antigen, T-Cell; D004247:DNA