Role of chicken IL-2 on γδ T-cells and Eimeria acervulina-induced changes in intestinal IL-2 mRNA expression and γδ T-cells

Continuous culture of concanavalin A (Con A)-activated spleen cells in the presence of chicken recombinant IL-2 (rIL-2) promoted preferential growth of γδ T-cells. These cells displayed a high level of spontaneous cytotoxicity against LSCC-RP9 tumor cells, an avian NK cell target. Stimulation of IL-2-dependent γδ T-cells with Con A induced IFN-γ and IL-2 mRNA transcripts, whereas stimulation with rIL-2 induced only IFN-γ mRNA. Subcutaneous injection of 3-week-old chickens with IL-2 DNA increased splenic cells, expressing the CD8 and γδ TCR antigens. To investigate the role of IL-2 and γδ T-cells in parasitic infection, chickens were orally infected with Eimeria acervulina and the expression of IL-2 mRNA transcripts in the spleen and duodenum and the percentage of γδ T-cells in the duodenum were examined. Following both, the primary and secondary infections, a significant enhancement of IL-2 mRNA transcripts in the spleen and intestine and increased percentage of intraepithelial γδ T-cells in the duodenum were observed. These results indicate that host immune responses to E. acervulina involve an up-regulation of IL-2 secretion and an increased duodenum γδ T-cells.