The bursa of Fabricius as a trapping mechanism for environmental antigens.

The bursa of Fabricius was isolated from gut-derived antigens by ligating the bursal duct on the 18th day of incubation. Ligation of the bursal duct (BDL) suppressed the bursal development, spontaneous germinal centre formation in the spleen and the development of serum "natural" agglutinins for bacteria or heteroerythrocytes. Moreover, administration of sterilized cecal contents into the bursal lumen at BDL led to normal level of serum "natural" agglutinins. These findings strongly suggest that the bursa of Fabricius possesses an antigen-dependent process which modulates the development of immune system. Antigen-trapping mechanism of the bursa may supply information about environmental antigens for this process.