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Endogenous IL-7 is associated with increased thymic volume in adult HIV-infected patients under highly active antiretroviral therapy

Ruiz-Mateos, Ezequiela; de la Rosa, Rafaela; Franco, Jaime Ma; Martinez-Moya, Manuelb; Rubio, Amaliac; Soriano, Nataliaa; Sanchez-Quijano, Armandoa; Lissen, Eduardoa; Leal, Manuela

Basic Science

Objective: Immune reconstitution after highly active antiretroviral therapy (HAART) in HIV-infected patients has led to an increase in the number of new CD4 T lymphocytes. Neolymphopoiesis in the thymus has been proposed as a mechanism in T-cell regeneration. Nevertheless, factors involved in the regeneration of T cells by thymic-dependent pathways in HIV-infected patients under HAART are still unknown and might be of relevance in HIV infection. The aim of this work was to study the role of IL-7 in the thymic rebound of HIV-infected adults under HAART.

Design: To study the association between IL-7 and thymic function-related markers, these variables were measured in 49 antiretroviral-naive HIV-infected patients at baseline and at weeks 12, 24, 36 and 48 of treatment.

Methods: Thymic function-related markers: thymic volume, naive phenotype, and T-cell receptor excision circles (TREC) bearing-cells, were evaluated by computed tomography, flow cytometry, and quantitative polymerase chain reaction, respectively. IL-7 levels were evaluated using a high sensitivity colorimetric enzyme-linked immunosorbent assay.

Results: At baseline, we found an inverse correlation between IL-7 levels and thymic function-associated parameters: thymic volume, naive T cells and TREC-bearing cells. After 48 weeks of therapy increased levels of thymic function-related markers along with a significant decrease in IL-7 levels were found. IL-7 levels at baseline were the only independently associated variable with respect to changes in thymic volume at weeks 12, 24 and 48 of follow-up.

Conclusion: These data suggest that IL-7 plays an important role in thymic rebound in adult HIV-infected patients under HAART.

From the aViral Hepatitis and AIDS Study Group, and bDepartment of Radiology, Virgen del Rocío University Hospital, and cDepartment of Medical Biochemistry and Molecular Biology, University of Seville, Seville, Spain.

Correspondence to: Manuel Leal MD, PhD, Grupo de Estudio Hepatitis Vírica y SIDA. Department of Internal Medicine, Virgen del Rocío University Hospital. Seville, Spain. Tel: +34 955 012396; fax: +34 955 012390; e-mail:

Received: 5 July 2002; revised: 28 October 2002; accepted: 29 November 2002.

© 2003 Lippincott Williams & Wilkins, Inc.