Non specific acid esterase activity in human periapical inflammatory cells.

The fine structural localization of non specific acid alpha-naphthyl acetate esterase activity (ANAE) in human periapical inflammatory cells was studied in sections of paraffin embedded tissue of 20 human periapical lesions (granulomas). Examination of specimens incubated with ANAE resulted in ANAE+ cells interpreted as T-lymphocytes, monocytes, macrophages, giant cells and plasma cells. ANAE- lymphocytes were interpreted as B cells. Our findings do not seem to confirm the presence among human periapical inflammatory cells of NK (natural killer) cells. T-lymphocytes were the most represented cellular type. The macrophages with ANAE+ reaction were numerous in all specimens observed and the variation in staining intensity could reflect a varying stage of activation. These findings allow conclusions about the role of T-lymphocyte mediated immune reaction in the pathogenesis of periapical lesions. The possibility that the activated T-lymphocytes within the periapical lesions may have a critical role in establishing and maintaining granuloma formation is also discussed.