IMMUNOCYTOCHEMICAL DISTRIBUTION OF HUMAN-PMN ELASTASE AND CATHEPSIN-GIN DENTAL-PULP

Components of primary (azurophilic) granules of polymorphonuclear leuk ocytes (PMNs) have been implicated as important mediators in pulpal in flammation. This anatomical study used ultracryoimmunocytochemical tec hniques and characterized and contrasted the subcellular distributions of human PMN elastase (PMN-E), PMN cathepsin-G (PMN-CG), and alpha-2 macroglobulin (alpha-2M) in healthy and inflamed dental pulps. Inflame d pulpal tissue sections revealed an intense distribution of PMN-E in the extracellular domain throughout the collagen matrix. PMN-E was als o localized in the perinuclear cytoplasm of PMNs and distributed in a random fashion. PMN-CG was localized intensely in the intracellular gr anules of PMNs and observed moderately within the extracellular matrix . Healthy pulpal tissues exposed to PMN-E and PMN-CG antibodies reveal ed no evidence of PMN infiltration and no specific labeling. Alpha-2M, a natural serum inhibitor of PMN-E and PMN-CG, was distributed in an intense fashion within the intravascular compartments of both inflamed and healthy pulpal samples. Immunogold-labeling for alpha-2M was obse rved in moderate amounts within the extravascular domain of inflamed p ulpal samples but only in mild amounts within the same area of healthy tissues. These results suggest that PMN-E and PMN-CG are released to the extracellular matrix of irreversibly inflamed teeth, enabling them to facilitate pulpal connective tissue destruction. Conversely, moder ate extravascular labeling for alpha-2M within inflamed samples sugges ts a physiological attempt at inhibiting the pulpal connective tissue destruction mediated by human PMN-E and PMN-CG.