Oral Presentation International Veterinary Immunology Symposium 2016

Immune response of porcine T lymphocytes (#24)

Irene M. Rodríguez-Gómez 1 2 , Stephanie C. Talker 1 , Tobias Käser 3 , Maria Stadler 1 , Sabine E. Hammer 1 , Armin Saalmüller 1 , Wilhelm Gerner 1
  1. Institute of Immunology, University of Veterinary Medicine, Vienna, Austria
  2. Department of Anatomy and Comparative Pathology, Faculty of Veterinary Medicine, University of Córdoba, Córdoba, Spain
  3. Vaccine and Infectious Disease Organization-International Vaccine Centre , Saskatoon, Saskatchewan, Canada

γδ T cells are a major subpopulation of circulating T cells in the pig, but their function is still poorly understood. The transcription factors GATA-3, T-bet and Eomesodermin (Eomes) play important roles in T-cell development and functional differentiation. However, their expression has not been studied in porcine γδ T cells yet. By using multi-color flow cytometry we investigated protein expression of these transcription factors in γδ thymocytes and mature γδ T cells as well as sorted and in vitro stimulated γδ T-cell subpopulations.

GATA-3 expression was found in the vast majority of γδ thymocytes. Minor populations of CD2+ γδ thymocytes expressed Eomes and T-bet and the latter was associated with a CD8αhigh phenotype. Similarly, extra-thymic CD2- γδ T cells expressed high levels of GATA-3. In contrast, T-bet expression was restricted to a subpopulation of CD2+ γδ T cells with a uniform CD8αhighCD27dim/-perforin+ phenotype across various analysed organs, including blood, spleen and lung tissue. Eomes+ γδ T cells were also only present among CD2+ cells but had mixed phenotypes for CD8α, CD27 and perforin. Moreover, Eomes+ γδ T cells were strongly enriched in the spleen compared to other analyzed organs. In vitro stimulation experiments with sorted CD2- γδ T cells revealed that following stimulation with ConA, IL-2, IL-12 and IL-18 these cells partially start to express CD2 and T-bet but keep their initial GATA-3 expression. Moreover, first experiments on cytokine production in the supernatants of these cultures indicate IFN-γ production but absence of IL-4, despite high levels of GATA-3 expression.

In conclusion, our data suggest a role for GATA-3 in γδ T cell development in the thymus and a type-1 differentiation of a subpopulation of CD2+ γδ T cells in extra-thymic locations. However, the relevance of the high expression of GATA-3 in extra-thymic CD2- γδ T cells requires further investigation.