IN-SITU HYBRIDIZATION AND IMMUNOCYTOCHEMICAL LOCALIZATION OF OSTEOLYTIC CYTOKINES AND ADHESION MOLECULES IN AMELOBLASTOMAS

Ameloblastomas produce interleukin-1-like activity that could explain some part of their osteolytic capability. However, the cellular source of this osteolytic activity is unknown. In the present study, cytokin es with known inflammatory and osteolytic activity, i.e., interleukin- 1 (IL-1), tumour necrosis factor (TNF), and interleukin-6 (IL-6), have been localised by immunocytochemistry and in situ hybridisation. The cellular adhesion receptors ICAM-1 E-selectin and VCAM-1 have also bee n immunolocalised, Immunocytochemistry demonstrated that all seven spe cimens showed positive staining for IL-1 alpha and IL-6 with these cyt okines being located in the stellate reticulum-like cells and vascular endothelium. Very faint staining for IL-1 beta was seen in four of se ven specimens. No reaction was seen for TNF-alpha. All specimens demon strated E-selectin staining in the vascular endothelium and ICAM-1 and VCAM-1 staining in the stellate reticulum-like cells and the endothel ium. In situ hybridisation for the cytokines showed the presence of mR NA of both IL-1 alpha and IL-6 in the stellate reticulum-like cells. F aint staining for IL-1 beta was also seen. No staining was seen for TN F These findings show that ameloblastomas synthesize two bone-modulati ng cytokines, IL-1 alpha and IL-6, and that these are synthesized main ly by the stellate reticulum-like cells. These tumours also contain a proportion of activated blood vessels in which endothelial cells expre ss the cellular adhesion receptors ICAM-1, E-selectin and VCAM-1.