[Tumor infiltrating regulatory T cells in human breast cancer and associated draining lymph nodes: an in-situ analysis].

Objective To retrospectively analyze the quantity and status of the tumor infiltrating regulatory T lymphocytes in breast cancer and the draining lymph nodes,and to elucidate the clinical pathologic significance.Methods Seventy-four breast cancer samples with excised axillary lymph nodes were typed and staged histopathologically.The regulatory T lymphocytes were labeled by immunohistochemistry using EnVision method with the monoclonal antibodies against CD25 and Foxp3,and the immunophenotype was analyzed.In addition,the expression of IFN-γ,IL-10 and TGF-β1 mRNA in lymphocytes of lymph nodes draining the tumors was detected by in situ hybridization with the corresponding specific oligo nucleaic acid probes.Results The number of CD25+ Foxp3+ T cells infiltrating the interstitium was much higher than that in the parenchymal tissue of the cancer.In the tumor draining lymph nodes,CD25+ cells and Foxp3+ cells were predominantly distributed in the paracortex with a proliferative pattern.TGF-β1,INF-γ and IL-10 mRNA positive cells showed a similar distribution pattern in the draining lymph nodes.Among the 39 cases with metastatic disease,the lymph nodes with metastases showed a much higher number of CD25+ Foxp3+ cells than that without metastases (23.5 vs 17.3 and 23.8 vs 15.5 ; P ＜0.05).However,there was no difference in the density of Foxp3+ CD25+ cells in the draining lymph nodes between the death and survival groups (P ＞ 0.05).Cytokine expression of TGF-β1,IL-10 and IFN-γ mRNA in the lymphocytes of draining lymph nodes in 24 cases showed that there were more IL-10 mRNA positive cells in the dead patients than that in the survived patients.A similar trend was observed for TGF-β1 mRNA positive cells but the difference was not statistically significant (P ＞ 0.05).The expression rate of TGF-β1 and IL-10 mRNA in the draining lymph nodes was proportional to that of CD25+ and Foxp3+ cells (P ＜ 0.05),and the expression of TGF-β1 positive cells was also proportional to that of IL-10 mRNA positive cells (P ＜ 0.01).The expression of IFN-γ mRNA among these groups showed no significance (P ＞0.05).Conclusions Regulatory T cells may play important roles in inhibiting the host antitumor immunity,and the presence of increased regulatory T cells and Th2-secreting cells in paracortex with a proliferative pattern in the tumor draining lymph nodes implies that the paracortical proliferation of draining lymph nodes may not reflect positive antitumor effects. Key words: Breast neoplasms; Tumor microenvironment; In situ hybridization; Lymphocytes,regulatory