Immunocytochemical study of human lymphoid tissues with monoclonal antibodies against S-100 protein subunits

The present study concerns the immunocytochemical localization of S-100 protein alpha and beta subunits in the cells of human lymphoreticular tissue and their related tumours. The alpha subunit is mainly localized in dendritic cells, most likely the dendritic reticulum cells (DRCs) located within the germinal centers, while the beta subunit is mainly localized in the interdigitating reticulum cells (IRCs) in the paracortical area and in Histiocytosis "X" cells. No immunoreactivity for either subunit was found in the majority of normal lymphocytes, macrophages, malignant lymphoma cells, or xanthoma cells. The DRCs and IRCs are generally considered to show different distribution in the lymphoid tissues and demonstrate some difference in their immunocytochemical and enzyme-histochemical features. It is suggested that S-100 subunits can be used as useful markers for these two types of dendritic cells and investigation of these subunits may provide more information for the study of human lymphoreticular system.