The effect of CpG-ODN on antigen presenting cells of the foal

M Julia BF Flaminio¹ , Alexandre S Borges² , Daryl V Nydam³ , David W Horohov⁴ , Rolf Hecker⁵ and Mary Beth Matychak¹

¹Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA

²Departamento de Clinica Veterinaria, Faculdade de Medicina Veterinaria e Zootecnia, Universidade Estadual Paulista 'Julio de Mesquita Filho', UNESP-Campus de Botucatu, SP, Brazil

³Department of Population Medicine and Diagnostics Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA

⁴Department of Veterinary Science, Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY, USA

⁵Qiagen GmbH, Hilden, Germany; current address Tübingen, Germany

author email corresponding author email

Journal of Immune Based Therapies and Vaccines 2007, 5:1doi:10.1186/1476-8518-5-1


Published:	25 January 2007

Abstract

Background

Cytosine-phosphate-guanosine oligodeoxynucleotide (CpG-ODN) has been used successfully to induce immune responses against viral and intracellular organisms in mammals. The main objective of this study was to test the effect of CpG-ODN on antigen presenting cells of young foals.

Methods

Peripheral blood monocytes of foals (n = 7) were isolated in the first day of life and monthly thereafter up to 3 months of life. Adult horse (n = 7) monocytes were isolated and tested once for comparison. Isolated monocytes were stimulated with IL-4 and GM-CSF (to obtain dendritic cells, DC) or not stimulated (to obtain macrophages). Macrophages and DCs were stimulated for 14–16 hours with either CpG-ODN, LPS or not stimulated. The stimulated and non-stimulated cells were tested for cell surface markers (CD86 and MHC class II) using flow cytometry, mRNA expression of cytokines (IL-12, IFNα, IL-10) and TLR-9 using real time quantitative RT-PCR, and for the activation of the transcription factor NF-κB p65 using a chemiluminescence assay.

Results

The median fluorescence of the MHC class II molecule in non-stimulated foal macrophages and DCs at birth were 12.5 times and 11.2 times inferior, respectively, than adult horse cells (p = 0.009). That difference subsided at 3 months of life (p = 0.3). The expression of the CD86 co-stimulatory molecule was comparable in adult horse and foal macrophages and DCs, independent of treatment. CpG-ODN stimulation induced IL-12p40 (53 times) and IFNα (23 times) mRNA expression in CpG-ODN-treated adult horse DCs (p = 0.078), but not macrophages, in comparison to non-stimulated cells. In contrast, foal APCs did not respond to CpG-ODN stimulation with increased cytokine mRNA expression up to 3 months of age. TLR-9 mRNA expression and NF-kB activation (NF-kB p65) in foal DCs and macrophages were comparable (p > 0.05) to adult horse cells.

Conclusion

CpG-ODN treatment did not induce specific maturation and cytokine expression in foal macrophages and DCs. Nevertheless, adult horse DCs, but not macrophages, increased their expression of IL-12 and IFNα cytokines upon CpG-ODN stimulation. Importantly, foals presented an age-dependent limitation in the expression of MHC class II in macrophages and DCs, independent of treatment.