Immunohistochemical observations of antigen presenting cells and follicular dendritic cells in the tonsil

In the present study, in order to investigate the behavior in the lymphatic system of phagocytic cells which incorporate potential antigen in the tonsile crypt, the distribution of HRP stained macrophages in the tonsillar system was observed with regard to changes with time. Furthermore, in the tonsillar tissue, in order to investigate the relationship among HRP marked macrophages, follicular dendritic cells and adhesion molecules, such as ICAM-1, immunological double staining was performed. It is open to discussion whether ICAM-1 plays an important role as an adhesive molecule in this migration of macrophages. Immunohistochemical double staining method detected a relation between anti-ICAM-1 antibody positive cells and antigen stained macrophages. In the stained area between anti-ICAM-1 antibodies and anti-DRC-1 antibodies, positive cells were clearly observed to have reticular form, particularly in the mature germinal center. This phenomenon implies that dendritic cells express ICAM-1 on the cell surface to contact other immunorelated cells and/or substances. In the inter-follicular space, anti-ICAM-1 antibody positive cells were observed to form a cluster composed of ICAM-1 positive cells, lymphocytes and HRP stained macrophages. This cluster may be considered the most primary stage of follicles or as triggering the creation of an inmature follicle.