Open Access

ARTICLE

Interleukin-9 stimulates the production of interleukin-5 in CD4⁺ T cells

Lionel F. Poulin¹, Claude Habran¹, Patrick Stordeur¹, Michel Goldman¹, Andrew McKenzie², Jacques Van Snick³, Jean-Christophe Renauld³, Michel Y. Braun¹

1 The Institute for Medical Immunology, Université Libre de Bruxelles, 8 rue Adrienne Bolland, 6041 Gosselies, Belgium
2 MRC Laboratory of Molecular Biology, Hills Road, Cambridge, United Kingdom
3 The Ludwig Institute for Cancer Research, Brussels branch, and the Experimental Medicine Unit, Catholic University of Louvain, Brussels, Belgium

* Corresponding Author: M.Y. Braun,

European Cytokine Network 2005, 16(3), 233-239.

Accepted 29 June 2005;

Abstract

We recently showed that interleukin-9 (IL-9), a Th2 cytokine, promotes IL-5-mediated rejection of allografts in mice. This observation led us to investigate the functional link between IL-9 and IL-5 production during alloreactive T cell responses in vitro and in vivo. Firstly, we found that IL-9 was produced by alloreactive Th2 cells, and IL-9 mRNA was detected in skin allograft during Th2-type rejection. We then established that IL-5 production was impaired in alloreactive Th2 cells isolated from IL-9-deficient mice and that optimal IL-5 production after allogeneic stimulation requires a functional IL-9 receptor (IL-9R) on the responding cells. Finally, the production of IL-5 by anti-CD3-stimulated CD4⁺ T cells was abolished by neutralization of IL-9. Despite the fact that IL-9 promotes IL-5 production by alloreactive T cells, IL-9-deficient recipients of skin allografts still developed eosinophilic graft infiltrates and neither IL-9 nor IL-9R deficiency modified Th2-type allograft rejection.

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