Antigen-binding cells in the cecal tonsil and Peyer's patches of the chicken after bovine serum albumin administration.

It has been previously reported in the chicken that the ellipsoid-associated cells (EAC), which are considered to be a type of splenic dendritic cell, migrate from the spleen into the blood after binding antigen on their surface. In the current study we traced the localization of these cells within two peripheral lymphoid organs, the cecal tonsil (CT) and the Peyer's patches (PP). The migration of the cells was followed by light microscopy using bovine serum albumin bound to biotin and conjugated to gold particles as a histochemically identifiable antigen detected as peroxidase reaction. The observations showed that the EAC after entering the circulating blood migrated into the lymphoid tissue of the CT and the PP. As a consequence, the antigen-binding cells were found in the diffuse lymphoid tissue and the germinal centers in both lymphoid organs. In the former location they were seen 24 h after the second antigen administration and in the germinal centers on Day 3. In addition, antigen-binding cells started to be observed in the lymphoid tissue at the same time as T and B cells were found to proliferate by using 5-bromo-2'-deoxyuridine. Based upon these findings, we suggested that the EAC have a role as antigen-transporting cells from the spleen to the CT and the PP via the blood stream. Furthermore, our results provided evidence that after the antigen-transporting EAC entered the above-mentioned organs, these cells behaved as antigen-presenting cells in both the T- and B-dependent areas.(ABSTRACT TRUNCATED AT 250 WORDS)