Isolation and characterization of inflammatory cells from the human periapical granuloma.

Twelve histologically-confirmed periapical granulomas were evaluated by conventional immunologic rosette assays for the presence of T-lymphocytes and complement receptor-bearing lymphocytes. A technique for dispersing the granuloma cells into suspensions was adopted to facilitate performance of the assays which were not applicable to tissue sections. Differential cell counts by an acridine orange vital dye method disclosed that the cell suspensions contained 30% macrophages, 44% lymphocytes, 15% plasma cells, and 12% neutrophils. Complement receptor-bearing cells comprised 17.9%, and T cells comprised 34.5% of the unseparated inflammatory cells. This study provides the first direct evidence of a predominance of thymic-derived lymphocytes in the lymphocyte compartment of the periapical granuloma. Analysis of the data shows that cell-mediated immunity most likely plays a role in the pathogenesis of the periapical granuloma.