Homeostatic role of IL-7 in HIV-1 infected children on HAART: association with immunological and virological parameters.
OBJECTIVE
To investigate the role of IL-7 in HIV-infected children on highly active antiretroviral therapy (HAART) and its association with laboratory parameters related to disease progression.


METHODS
A cross-sectional study in 31 vertically HIV-infected children (median age 8.4 y) treated with HAART, and a longitudinal study in four of those same children was carried out. In both studies, viral load, CD4+ T-cell counts, thymic production of T cells by TCR rearrangement excision circles (TRECs), IL-7 plasma levels and viral phenotype were determined.


RESULTS
IL-7 levels were higher in HIV-infected children than in age-matched, uninfected controls. In addition, HIV children with CD4+ T cells between 200 and 500 T cells/mm3 had higher IL-7 levels and lower TREC values than HIV-infected children with CD4+ T cells >500 T cells/mm3. IL-7 levels were higher in children with syncytium-inducing (SI) phenotype than in those with non-syncytium-inducing (NSI) variants. During the follow-up of four HIV children, the decrease in viral load after HAART was always associated with a recovery of CD4+ T cells and TRECs, which was followed by a decrease in IL-7 returning to the levels present prior to the drop in CD4+ T cells. The four HIV-infected children had SI/X4 isolates in PBMC before HAART, and the viral phenotype switched to NSI/R5 after HAART.


CONCLUSIONS
Our data suggest that IL-7 plays a key role in the maintenance of T-cell homeostasis in HIV-infected children on HAART, both through peripheral expansion and through a thymus-dependent mechanism.
Laboratorio de Inmuno-Biología Molecular, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
S
S
Resino
I
I
Galán
R
R
Correa
Lucia
L
Pajuelo
J M
JM
Bellón
Maria A
MA
Muñoz-Fernández
D000293:Adolescent; D023241:Antiretroviral Therapy, Highly Active; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D015329:Gene Rearrangement, T-Lymphocyte; D015658:HIV Infections / Q000188:drug therapy / Q000276:immunology* / Q000821:virology*; D015497:HIV-1; D006801:Humans; D015851:Interleukin-7 / Q000097:blood*; D008137:Longitudinal Studies; D016555:Matched-Pair Analysis; D010641:Phenotype; D012367:RNA, Viral / Q000097:blood; D018709:Statistics, Nonparametric; D016176:T-Lymphocyte Subsets / Q000378:metabolism; D013950:Thymus Gland / Q000276:immunology; D019562:Viral Load
D015851:Interleukin-7; D012367:RNA, Viral