Human T-lymphocyte subpopulations in periapical lesions.

Both B-lymphocyte-and T-lymphocyte-mediated immunologic reactions have been implicated in the pathogenesis of human periapical lesions. The purpose of this study was to identify various subpopulations of T-lymphocytes in these lesions. Fifteen periapical lesions were obtained during periapical surgery. Each specimen was quick-frozen and stored in liquid nitrogen. Immunoperoxidase staining for the presence of T-lymphocyte subpopulation, was done with the use of the monoclonal antibody and Vecta-stain ABC/peroxidase kit. Cryostat tissue sections were incubated with 3% normal horse serum. Specific monoclonal antibody (Coulter T4, T8, T11) was placed on the section, washed, and then covered with biotinylated antibody to mouse IgG. After TRIS HC1 washing, the ABC/peroxidase solution was placed on the section and 3,3-diaminobenzidine was applied; the section was washed and then counterstained with 2% methyl green. After dehydration, sections were mounted and examined under the light microscope. The presence of lymphocytes was confirmed by the appearance of brown rings around cells with lymphocyte morphology. Fourteen lesions were diagnosed as granuloma and stained positively for pan T-lymphocytes (T11), T helper cells (T4), and T cytotoxic cells (T8). The remaining specimen, diagnosed as an apical scar, contained no T-lymphocytes. The presence of T-cells in periapical lesions indicates that cell-mediated reactions participate in the pathogenesis of these lesions.