Submitted to: Immunology Research Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2003
Publication Date: 12/1/2003
Citation: Holt, P.S. 2003. Evaluation of the chicken crop (ingluvies) as a model system for following mucosal immunity in chickens. Immunology Research Workshop. Interpretive Summary:
Technical Abstract: The crop (ingluvies) is an enlargement or out pouching of the esophagus proximal to the proventriculus, or glandular stomach and functions primarily in a food storage role for avian species. While recent work has shown the crop can be colonized with pathogens such as Salmonella, little information is available regarding the presence of any immune response within this organ. During a recent study investigating mucosal immunity to Salmonella enteritidis (SE) in the alimentary tract of White Leghorn chickens, we discovered the presence of substantial titers of IgA specific for SE in samples from crops removed from SE-infected, but not from noninfected, birds. Histological examination of the crop tissues found a paucity of lymphocytes in noninfected birds but lymphocyte aggregates were detected in the crop mucosa by 2 weeks post infection which increased in size and number thereafter. Because of the easy access to this organ orally, a crop lavage system was developed where a narrow diameter plastic tubing attached to a syringe was inserted down the esophagus into the crop. A flush solution was administered into the crop and immediately aspirated back into the syringe, with minimal discomfort to the bird and allowing multiple samplings of the same live birds over time. While specific IgA responses were the most robust, high levels of SE-specific IgG were also detected. Comparing IgA titers in crop lavage samples vs intestinal flushes from individual SE-infected birds, a very good correlation between titers of the two sample types was obtained, indicating that crop immunity may be used as an easy model for following mucosal immunity in a bird following infection. Studies are currently underway to determine crop immune responses in chickens infected with other pathogens, the prevalence of lymphoid tissues in crops from different avian species, the phenotypes of lymphocyte populations that develop in the chicken crop post infection and the importance of mucosal invasion in driving the development of this lymphoid tissue.