LOCALIZATION OF SPLENIC CELLS WITH ANTIGEN-TRANSPORTING CAPABILITY INTHE CHICKEN

Background: The objective of the present study is to investigate the m igration pattern of the splenic dendritic cell of the chicken named th e ellipsoid-associated cell (EAC) from the site of initial location at the periphery of the ellipsoid to the splenic T- and B-dependent area s. Methods: Bovine serum albumin bound to biotin and conjugated to gol d particles was used as a histochemically identifiable antigen detecte d as a peroxidase reaction. The antigen was intravenously injected, an d subsequently its pattern of distribution in a time sequence and with in the tissue was examined at the light and electron microsocopy level s. In addition, an hour prior to sacrifice, the chickens received a si ngle injection of the thymidine analogue 5-bromo-2'-deoxyuridine, in o rder to quantify the number of DNA synthesizing cells and to establish a relationship between the migrating EAC and the rate of mitosis in t he white pulp. Results: The observations showed that between 12 hours and 3 days after the second antigen administration the labeled EAC, wh ich was first located around the ellipsoid, progressively reached furt her areas with time towards the periarteriolar lymphoid sheaths, where newly formed germinal centers appeared. Furthermore, the rate of cell proliferation within the white pulp was associated with the arrival o f the antigen-transporting EAC. Conclusions: The results suggest that migrating EAC have a role as both antigen-transporting cell and antige n-presenting cell in the T- and B-dependent areas, as a result of whic h migrating EAC is transiently found in periellipsoidal white pulp, th en periarteriolar lymphoid sheaths, and finally germinal centers, wher e it may function as an interdigitating cell or as a follicular dendri tic cell, depending on its location. Thus, we conclude that the EACs a re precursors of both interdigitating and follicular dendritic cells. (C) 1995 Wiley-Liss, Inc.