Increases in CD4+ T lymphocytes occur without increases in thymic size in HIV-infected subjects receiving interleukin-2 therapy.
OBJECTIVE
To examine the potential contribution of the thymus to CD4+ T-lymphocyte increases in HIV-infected patients receiving intermittent interleukin-2 (IL-2) therapy.


METHODS
Fifteen HIV-infected patients treated with antiretroviral regimens who were enrolled in a study of intermittent IL-2 therapy and were willing to undergo serial thymic computed tomography (CT) were prospectively studied.


METHODS
Thymic CT was performed before and approximately 6 and 12-17 months after intermittent IL-2 therapy was started. Scans were graded in a blinded manner. Changes in lymphocyte subpopulations were determined by flow cytometry.


RESULTS
Statistically significant increases in CD4+ T lymphocytes occurred with IL-2 administration, with a preferential increase in naive relative to memory CD4+ T cells. Despite this increase in naive CD4+ T cells, overall there was a modest decrease in thymic volume observed during the study period. No correlation was found between changes in thymic volume indices and total, naive, or memory CD4+ T-lymphocyte counts.


CONCLUSIONS
These findings demonstrate that the profound CD4+ T-lymphocyte increases seen with intermittent IL-2 administration are not associated with increases in thymic volume and more likely are due to peripheral expansion rather than increased thymic output.
Lu
Amy C
AC
Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Jones
Elizabeth C
EC
Chow
Catherine
C
Miller
Kirk D
KD
Herpin
Betsey
B
Rock-Kress
Diane
D
Metcalf
Julia A
JA
Lane
H Clifford
HC
Kovacs
Joseph A
JA
D000328:Adult; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology*; D005434:Flow Cytometry; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology; D015497:HIV-1; D006801:Humans; D007376:Interleukin-2 / Q000627:therapeutic use*; D008137:Longitudinal Studies; D008297:Male; D011446:Prospective Studies; D013950:Thymus Gland / Q000187:drug effects* / Q000276:immunology* / Q000502:physiology; D014057:Tomography, X-Ray Computed
D007376:Interleukin-2