EXPRESSION OF MEMBRANE ALKALINE-PHOSPHATASE ACTIVITY ON GINGIVAL FIBROBLASTS IN CHRONIC INFLAMMATORY PERIODONTAL-DISEASE

We investigated the expression of membrane alkaline phosphatase (ALP) activity on fibroblasts in inflamed gingiva from 7 patients with adult periodontitis. ALP activity was ultrahistochemically detected by a cerium-based capture method. The degree of ALP activity was estimated by morphometric analysis of the percentage of the perimeter on which ALP reaction product was deposited. Fibroblasts in the non-inflammatory connective tissue were surrounded by bundles of collagen fibrils, and the majority of these fibroblasts showed ALP-negative or weakly ALP-positive reaction. By contrast, fibroblasts in the inflammatory connective tissue were either surrounded by a non-collagenous substance or in contact with inflammatory cells, and the majority of these fibroblasts showed a strong ALP-positive reaction. These results suggest that the expression of membrane ALP activity on gingival fibroblasts is induced by microenvironmental changes associated with the loss of contact between the cells and the extracellular collagenous matrix during inflammatory reactions.