Phenotypic characterization of-specific chicken T-cells responding toparasite antigen re-stimulation.

Abstract

Coccidiosis, caused by protozoan parasites of genus, is a disease with large impact on poultry production worldwide. It is well known thatimmunity is dependent on Th1-type responses.assessment of-specific T-cell activity would therefore be a valuable research tool but has so far proven difficult to establish.The present study aimed to evaluateinduced blast transformation and CD25 expression in defined chicken T-cell populations as a measure ofimmunity.Threeinfection experiments were performed and PBMC and/or spleen cells were collected between 6 and 16 days after infection of chickens. Cells were stimulatedwithantigens and T-cell activation was assessed by immunofluorescence labelling and flow cytometry.The results consistently showed statistically significantspecific activation of TCRα/β+T cells within a 'window' from 8 to 14 days after infection for both spleen cells and PBMC. Responding T-cells were identified as CD4+CD8-, CD4+CD8αα+ and CD4-CD8αβ+ where the CD4+CD8αα+ cells generally showed the highest responses. All three of these TCRα/βT-cell subsets showed significantinduced blast transformation and/or CD25 expression albeit not always in concert on the same days after infection indicating complex kinetics of T-cell responses. In general, responses were higher for spleen cells compared to PBMC for all responding T-cell populations.This methodology shows promise to study-specific T-cells, e.g. to evaluate vaccine responses. Results indicated that a Th1-type response was induced and suggested a role for CD4+CD8αα+ cells inimmunity.