Free Access
Vet. Res.
Volume 40, Number 1, January-February 2009
Number of page(s) 14
Published online 18 October 2008
How to cite this article Vet. Res. (2009) 40:06
How to cite this article: Vet. Res. (2009) 40:06
DOI: 10.1051/vetres:2008044

Subpopulations of bovine WC1+ $\gamma\delta$ T cells rather than CD4+CD25$^{\rm high}$ Foxp3+ T cells act as immune regulatory cells ex vivo

Aad Hoek1, Victor P.M.G. Rutten1, 2, Jolanda Kool1, Ger J.A. Arkesteijn1, Ruth J. Bouwstra3, Ildiko Van Rhijn1 and Ad P. Koets1, 3

1  Division of Immunology, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
2  Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, South Africa
3  Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands

Received 5 May 2008; accepted 15 October 2008; published online 18 October 2008

Abstract - Regulatory T cells (Treg) are regarded essential components for maintenance of immune homeostasis. Especially CD4+CD25$^{\rm high}$ T cells are considered to be important regulators of immune reactivity. In humans and rodents these natural Treg are characterized by their anergic nature, defined as a non-proliferative state, suppressive function and expression of Foxp3. In this study the potential functional role of flowcytometry-sorted bovine white blood cell populations, including CD4+CD25$^{\rm high}$ T cells and $\gamma\delta$ T cell subpopulations, as distinct ex vivo regulatory cells was assessed in co-culture suppression assays. Our findings revealed that despite the existence of a distinct bovine CD4+CD25$^{\rm high}$ T cell population, which showed Foxp3 transcription/expression, natural regulatory activity did not reside in this cell population. In bovine co-culture suppression assays these cells were neither anergic nor suppressive. Subsequently, the following cell populations were tested functionally for regulatory activity: CD4+CD25$^{\rm low}$ T cells, WC1+, WC1.1+ and WC1.2+ $\gamma\delta$ T cells, NK cells, CD8+ T cells and CD14+ monocytes. Only the WC1.1+ and WC1.2+ $\gamma\delta$ T cells and CD14+ monocytes proved to act as regulatory cells in cattle, which was supported by the fact that these regulatory cells showed IL-10 transcription/expression. In conclusion, our data provide first evidence that cattle CD4+CD25$^{\rm high}$Foxp3+ and CD4+CD25$^{\rm low}$ T cells do not function as Treg ex vivo. The bovine Treg function appears to reside in the $\gamma\delta$ T cell population, more precisely in the WC1.1+ and the WC1.2+ subpopulation, major populations present in blood of cattle in contrast to non-ruminant species.

Key words: bovine / T cells / regulation / cytokines / suppression

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© INRA, EDP Sciences 2008