Characteristics and functional aspects of nonlymphoid cells in rat germinal centers, recognized by two monoclonal antibodies ED5 and ED6.

In this study two newly developed monoclonal antibodies, ED5 and ED6, are described, which specifically recognize nonlymphoid cells in B cell follicles of spleen and lymph nodes. Enzyme and immunocytochemical techniques demonstrated that ED5 and ED6 stain two different types of reticulum cells. The staining patterns were compared with those of the monoclonal antibody Ox2. ED5+ cells are able to retain immune complexes and are considered to be the follicular dendritic cell; in contrast ED6+ lack this capacity. Peyer's patches contain many ED6+ and Ox2+ cells but are completely devoid of ED5+ cells. After the application of immunomodulatory agents, like X-irradiation, cyclophosphamide and lipopolysaccharide, ED5+ and ED6+ cells remain detectable. The nature of the new type of dendritic reticulum cell in lymphoid follicles, recognized by ED6, is discussed.