Loss of IL-7Ra is Associated With CD4+ T Cell Depletion, High IL-7 Levels and CD28 Down-regulation in HIV Infected Patients

BioMed Central Page 1 of 1 (page number not for citation purposes) Retrovirology Open Access Poster presentation Loss of IL-7Ra is Associated With CD4+ T Cell Depletion, High IL-7 Levels and CD28 Down-regulation in HIV Infected Patients Bence Rethi*‡1, Caroline Fluur1, Ann Atlas2, Sven Grützmeier3, Angelo De Milito1, Éva Rajnavölgyi4 and Francesca Chiodi1 Address: 1Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden, 2Infectious Diseases Unit, Karolinska University Hospital, Solna, Sweden, 3Gay Men's Health Clinic, The Soder Hospital, Stockholm, Sweden and 4Institute of Immunology, University of Debrecen, Hungary Email: Bence Rethi* - [email protected] * Corresponding author ‡Presenting author Interleukin-7 (IL-7) is a survival factor for naïve and memory T lymphocytes and it also increases T cell proliferation during lymphopenic conditions. Elevated levels of IL-7 have been found in the blood of HIV+ patients, which was considered as a homeostatic response to peripheral T cell depletion. We showed that HIV infection is associated with an increased proportion of IL-7Ra low/negative peripheral T lymphocytes. Down-regulation of IL-7Rα on T cells was correlated with the depletion of CD4+ T cells and also with the increased concentration of serum IL-7. The decreased IL-7Rα expression resulted in the reduced survival capacity of T cells in presence of IL-7 and was associated with low Bcl-2 expression. Mostly the memory T cells down-regulated the IL-7Rα and we found a strong association between CD28 and IL-7Rα down-regulation. Accordingly, only CD28+ T cells responded to IL-7 with strong Bcl-2 upregulation. The positive effects of IL-7 on survival and homeostatic proliferation of T cells might be severely impaired in HIV- infected individuals due to the decreased IL-7Rα expression. Chronic T cell activation may lead to an overall decrease of IL-7 mediated survival signals in HIV-infected individuals. from 2005 International Meeting of The Institute of Human Virology Baltimore, USA, 29 August – 2 September 2005 Published: 8 December 2005 Retrovirology 2005, 2(Suppl 1):P84 doi:10.1186/1742-4690-2-S1-P84 <supplement> <title> <p>2005 International Meeting of The Institute of Human Virology</p> </title> <note>Meeting abstracts – A single PDF containing all abstracts in this Supplement is available here. [link 'here' using 'a href' to: <url>http://www.biomedcentral.com/content/pdf/1742-4690-2-S1-full.pdf</url>]</note> </supplement>