RESUMEN
Both B-lymphocyte- and T-lymphocyte-mediated immunologic reactions have been implicated in the pathogenesis of human periapical lesions. Thirteen periapical lesions were obtained during periapical surgery, frozen and serially sectioned. Monoclonal antibodies and indirect immunofluorescence techniques were used to compare the distribution of lymphocyte subpopulation in the periapical lesions. The proportions of total T-cells [T11], inducer/helper T-cells [T4+] and cytotoxic suppressor T cells [T8] were determined. No significant statistical difference was found between the number of T helper cells and that of the T cytotoxic cells. The presence of T-cells in periapical lesions indicated that cell-mediated reactions participate in the pathogenesis of these lesions