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.
Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Amy C
AC
Lu
Elizabeth C
EC
Jones
Catherine
C
Chow
Kirk D
KD
Miller
Betsey
B
Herpin
Diane
D
Rock-Kress
Julia A
JA
Metcalf
H Clifford
HC
Lane
Joseph A
JA
Kovacs
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