Method: : We selected 50 cases of human periapical lesions: 20 cases of PGs, 20 RCs and 10 RRCs. For each specimen, were identified 5 random microscopic fields of higher immunoexpression in a 100x magnification. Subsequently, all immunostained cells were counted at 400x magnification, in order to establish the average of positive cells for each case. The specimens were also classified according to the intensity of the inflammatory infiltrate (mild/moderate or intense) and the thickness of the epithelial lining in the cystic lesions (atrophic or hyperplastic), in order to correlate these data with the immunoexpression of FoxP3.
Result: The Kruskal-Wallis test revealed statistically significant differences between groups, with PGs displaying greater median of FoxP3-positive lymphocytes compared with the RCs and RRCs (p <0.001). The Mann-Whitney test revealed a median of positive cells significantly higher in lesions with intense inflammatory infiltrate compared with lesions with infiltration mild/moderate (p = 0.003). Finally, the Mann-Whitney test revealed median of positive lymphocytes significantly higher in cysts with hyperplastic epithelium compared with cysts presenting atrophic epithelium (p = 0.009).
Conclusion: Increased expression of T regulatory cells was observed in PGs, in lesions with intense inflammatory infiltrate and in cysts with hyperplastic epithelium. Thus, these cells may be involved in inhibiting T cells proliferation and play regulatory functions in the control of local immune-inflammatory processes in periapical lesions.