Expression of ICAM-1, VCAM-1 and ELAM-1 in angiofollicular lymph node hyperplasia (Castleman's disease): evidence for dysplasia of follicular dendritic reticulum cells

The inducible adhesion molecules mediate important functions in the lymphoid tissues. We have investigated the expression of intercellular adhesion molecule 1 (ICAM‐1), endothelial leucocyte adhesion molecule 1 (ELAM‐1), vascular cell adhesion molecule 1 (VCAM‐1), and platelet endothelial cell adhesion molecule (PECAM/CD31), using immunocytochemistry on cryostat sections of five lymph nodes from patients with Castleman's disease of the hyaline‐ vascular type. All five cases were characterized by marked hyperplasia of follicular dendritic reticulum cells, which were extensively present even in the mantle zone. Hyperplastic follicular dendritic reticulum cells showed marked expression of VCAM‐1, and weak expression of ICAM‐1. In two cases, several dysplastic giant cells with aberrant, polyploid nuclei showed aberrant expression of ELAM‐1, an endothelium‐restricted molecule. Dysplastic giant cells were positive with DRC‐1 (an antibody to dendritic reticulum cells). VCAM‐1 and occasionally ICAM‐1, were negative for the endothelial cell markers factor VIII‐related antigen and CD31 and were non‐proliferating (Ki‐67‐). Cells positive for ICAM‐1 or VCAM‐1 were rare in the interfollicular areas. In all cases vascular hyperplasia was prominent, but endothelial cells were poorly activated in terms of expression of inducible adhesion molecules and of HLA‐DR antigens. The possibility that dysplastic follicular dendritic reticulum cells have a pathogenetic role in Castleman's disease is discussed.