ANTIGEN-BINDING CELLS IN THE CECAL TONSIL AND PEYERS-PATCHES OF THE CHICKEN AFTER BOVINE SERUM-ALBUMIN ADMINISTRATION

It has been previously reported in the chicken that the ellipsoid-asso ciated cells (EAC), which are considered to be a type of splenic dendr itic cell, migrate from the spleen into the blood after binding antige n 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 follo wed by light microscopy using bovine serum albumin bound to biotin and conjugated to gold particles as a histochemically identifiable antige n detected as peroxidase reaction. The observations showed that the EA C after entering the circulating blood migrated into the lymphoid tiss ue of the CT and the PP. As a consequence, the antigen-binding cells w ere found in the diffuse lymphoid tissue and the germinal centers in b oth 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 lym phoid tissue at the same time as T and B tells were found to prolifera te by using 5-bromo-2'-deoxyuridine. Based upon these findings, we sug gested 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 re sults provided evidence that after the antigen-transporting EAC entere d the above-mentioned organs, these cells behaved as antigen-presentin g cells in both the T- and B-dependent areas. We concluded that after entering the CT and the PP, the antigen-transporting EAC become interd igitating cells or follicular dendritic cells depending on their locat ion in the lymphoid tissue.