Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2003
Publication Date: N/A
Interpretive Summary: Lack of basic information concerning the development of poultry immune system hinders rapid progress in the development of logical control strategies against poultry diseases. In this study, scientists at Semmelweis University, Hungary, collaborated with scientists at ARS and University of Munich to investigate how immune cells develop in the bursa. The results demonstrated that the expression of bursal antigen detected by the mouse antibody against K-1 (developed at ARS) is an important event which occurs during the embryogenesis of poultry. Furthermore, the new finding that the cells which express the K1 antigen may represent the precursor cells of bursal secretory dendritic cells enhances our understanding of how poultry immune system develops. This study provides new knowledge concerning the development of bursal dendritic cells and will help poultry scientists to devise new ways to enhance innate immunity of poultry.
The immunocytochemical study of the K-1 monoclonal antibody indicates that the epithelial components of the bursa of Fabricius of the chicken and guinea fowl express the K-1 positive molecule. During embryogenesis, the K-1 antigen expression appers together with the bud-formation. As the number of B cells increases in the developing follicle, the K-1 expression gradually diminishes in the medullary reticular epithelial cells and completely ceases by hatching, which suggests that the molecule is developmentally regulated. After hatching, the expression of the molecule is restricted to the sealing off zone of the lymphoepithelial or medullary region of the follicle: i.e. to the cortico-medullary (CM) epithelial cells and the follicle associated epithelium (FAE) supporting cells in guinea fowl and to the latter ones in the chicken. The expression of the K-1 antigen by these epithelial components may support their structural identity. After hatching, the K-1 molecule is restricted to the CM epithelial cells and/or FAE supporting cells, which suggests that the function of the embryonic epithelial bud is taken over by the CM epithelial cells. The K-1 positive CM epithelial cells form arches, which encompass blast-like cells. The possible relationship of the CM epithelial cells and blast like cells, which may represent the precursors of bursal secretory dendritic cells is discussed.