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 ce rium-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 c onnective tissue were surrounded by bundles of collagen fibrils, and t he majority of these fibroblasts showed ALP-negative or weakly ALP-pos itive reaction. By contrast, fibroblasts in the inflammatory connectiv e tissue were either surrounded by a non-collagenous substance or in c ontact 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 bet ween the cells and the extracellular collagenous matrix during inflamm atory reactions.