Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 30, 2000
Publication Date: N/A
Interpretive Summary: Avian coccidiosis is caused by several different species of Eimeria parasites. Infection with coccidia causes severe intestinal damages and poor nutrient absorption. Although coccidiosis is currently managed by a drug theraphy,high incidence of drug resistant Eimeria field strains urges the development of novel control strategy against coccidiosis. However, the development of novel control strategy for coccidiosis is hampered by our lack of understanding of the immunobiology of parasite-host. In this paper, ARS scientists investigated the role of interleukin-2 (IL-2), soluble factor which is secreted by activated T-cells. These scientists showed for the first time that Eimeria parasites activate the intestinal T lymphocytes to produce IL-2 and increase the number of local T-lymphocytes. This paper indicates that the production of IL-2 by intestinal lymphocytes is an important feature of the local host immunity. These findings will increase our understanding of host immunity against Eimeria and aid the development of new control strategy for coccidiosis by poultry industry
Continuous culture of concanavalin A (ConA)-activated spleen cells in the presence of recombinant IL-2 (rIL-2) promoted preferential growth of gamma- delta 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 gamma-delta T-cells with ConA induced IFN-gamma and IL-2 mRNA transcripts whereas stimulation with rIL-2 induced only IFN-gamma mRNA. Subcutaneous injection of rIL-2 DNA increased splenic cells expressing the CD8 and gamma-delta TCR antigens. To investigate the role of IL-2 and intestinal cells in parasitic infection, 3-week-old chickens were orally infected with Eimeria acervulina and the expression of IL-2 mRNA transcripts in the spleen and duodenum and the percentage of gamma-delta T-cells in the duodenum were examined. Following both primary and secondary infections, a significant enhancement of IL-2 mRNA transcripts in the spleen and intestine and increased percentage of intraepithelial gamma-delta 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 gamma-delta T-cells.