Cytotoxic T lymphocytes versus streptococcal colonization in periapical granulomas.

Seventeen dental periapical lesions were investigated to study bacterial colonization. Periapical lesions, obtained after apicotomy, were also enzymatically desegregated to quantitatively analyze lymphocyte subpopulations by flow cytometry. Fourteen samples yielded a positive bacterial growth when homogenized and cultured. We isolated enough lymphocytes to make flow cytometric analysis from 12 samples. A significant increase in interleukin-2 receptor and ICAM-1 molecule expression on T cells was found, compared with peripheral blood lymphocytes. Furthermore, a decreased expression of interleukin-2 receptors and HLA DR molecules on CD8+ T cells was found in granulomas predominantly colonized by Streptococcus spp., compared with lesions predominantly colonized by strict anaerobes.