Effects of exogenous IL-2 administration on the homeostasis of CD4+ T lymphocytes

• Published in: Journal of clinical immunology 2004-09, Vol.24 (5), p.503-514
• Main Authors: Foussat, Arnaud, Bouchet-Delbos, Laurence, Couderc, Jacques, Berrebi, Dominique, German-Fattal, Michèle, Maillot, Marie-Christine, Durand-Gasselin, Ingrid, Galanaud, Pierre, Di Santo, James P, Emilie, Dominique
• Format: Article
• Language: English
• Subjects: Adjuvants, Immunologic - pharmacology; Animals; CD4-Positive T-Lymphocytes - drug effects; CD4-Positive T-Lymphocytes - metabolism; Homeostasis - drug effects; Humans; Interleukin-2 - pharmacology; Interleukin-7 - deficiency; Lymphoid Tissue - cytology; Mice; Receptors, Interleukin-2 - genetics; Receptors, Interleukin-2 - metabolism; RNA, Messenger - metabolism; Thymus Gland - cytology
• ISSN: 0271-9142; 1573-2592
• DOI: 10.1023/B:JOCI.0000040921.82055.91

IL-2 is currently used in HIV-infected patients to treat CD4+ T lymphopenia. In order to document a mechanism accounting for its capacity to restore immune function, we studied the effects of IL-2 administration in mice. IL-2 treatment of C57BL/6 mice for 4 days leads to a transient accumulation of CD4+ T lymphocytes. Whereas memory and activated CD4+ T lymphocytes accumulate after IL-2 treatment in both lymphoid and nonlymphoid organs, naive CD4+ T cells only accumulate in the former. IL-2 transiently increases CD4+ T lymphocyte numbers in lymphopenic IL-7(-/-) mice. Studies in T-cell-reconstituted Rag(-/-) gamma c(-/-) mice and in thymectomized mice demonstrated that IL-2 acts directly on peripheral CD4+ T lymphocytes. In vivo labeling of thymocytes showed that IL-2 also stimulates the release of CD4+ thymocytes from the thymus. Therefore, IL-2 treatment acts centrally and peripherally to increase the size of the naive CD4+ T lymphocyte compartment. This dual activity of IL-2 treatment may influence the quality of restoration of this compartment, especially regarding the ability to reconstitute a normal T lymphocyte repertoire.