IMMUNOLOCALIZATION OF INTERSTITIAL COLLAGENASE (MMP-1) AND TISSUE INHIBITOR OF METALLOPROTEINASES-1 (TIMP-1) IN RADICULAR CYSTS

To investigate the mechanisms involved in expansion of radicular cysts , monoclonal antibodies against interstitial collagenase (MMP-1) and t issue inhibitor of metalloproteinases-1 (TIMP-1) were used to localize the sites of MMP-1 and TIMP-1 expression in 30 radicular cysts. Posit ive MMP-1 staining was detected in the lining epithelium and subepithe lial fibroblasts, macrophages, endothelial cells and osteoblasts/osteo cytes in all specimens. Positive TIMP-1 staining was identified in ost eoblasts/osteocytes and endothelial cells of all specimens, and in the lining epithelium and subepithelial fibrous connective tissue wall of five radicular cysts with an intense inflammatory cell infiltrate. Th e number and distribution of positive cells for MMP-1 or TIMP-1 varied widely among individual specimens, but strong immunostaining was cons tantly detected at sites with prominent subepithelial inflammation. Re sults here support the hypothesis that MMP-1 may play an important rol e in the expansion of radicular cysts. The absence of TIMP-1 expressio n in lining epithelium and subepithelial fibroblasts and macrophages i n most cases studied indicated that an imbalance between MMP-1 and TIM P-1 production may lead to radicular cyst expansion.