Submitted to: International Immunology Congress
Publication Type: Abstract Only
Publication Acceptance Date: 5/20/2005
Publication Date: 6/25/2005
Citation: Holt, P.S., Vaughn, L.E., Moore, R.W., Gast, R.K. 2005. Development of lymphoid tissues in the crops of hens infected with salmonella enterica subspecies enterica serovar enteritidis. International Immunology Congress. Interpretive Summary:
Technical Abstract: Background: The avian crop (ingluvies) is a ventral diverticulum of the esophagus, located proximal to the proventriculus (glandular stomach). There has been little information available regarding immune responses within this organ. Recently, substantial titers of IgA specific for Salmonella enterica serovar Enteritidis (SE) were observed in crop samples taken from infected birds. Histological examination of crop tissue revealed prominent lymphoid aggregates within the lamina propria of these SE-challenged birds. The current study was initiated to further characterize such lymphoid tissue of the crop. Methods. White Leghorn chickens were infected with SE and 8 birds were sacrificed weekly. Crops were excised, fixed in 10% formalin, and serial cut tissue slides were prepared for staining. Crop morphology and crop lymphoid tissue status were assessed on H&E stained slides. IHC using monoclonal anti-chicken CD45 and Bu-1 antibodies facilitated the evaluation of crop sections for leukocyte and B cell presence respectively. Plasma cells were identified using the general stain methyl green-pyronin Y(MGP). Results. Organization of lymphoid cells into aggregates by 2 weeks post infection was observed in the crop lamina propria of SE challenged chickens. These lymphoid formations progressively increased in size, number and complexity in subsequent weeks. Crops from noninfected birds had minimal lymphocytic presence. A generalized diffuse staining for CD45+ cells was observed within the aggregates while Bu-1+ staining cells were found to be generalized or sometimes presented as an intensified staining region involving the cells that were most closely associated toward the lumen. MGP revealed plasma cells located scattered within or at peripheral borders of the aggregates. Conclusions. The development of organized lymphoid tissue within the crop lamina propria indicates that the observed SE specific IgA antibody response in the crop is generated at least partly in the crop. As intestinal pathogens must transit the crop to reach their target organs, the crop may be an important site to elicit protective antibodies to halt or ameliorate the infection.