Background: CD8+ cytotoxic T lymphocytes have been recently divided based on their cytokine expression profile.
Objective: To evaluate the percentages of CD8+ lymphocytes and their effector subsets including Tc1, Tc2 and Tc17 in the tumor draining lymph nodes (TDLNs) of patients with breast cancer.
Methods: Single cell suspensions were obtained from TDLNs of 42 patients with breast cancer. Staining of the cell surface markers and intracellular cytokines was performed using appropriate fluorochrome-conjugated antibodies. The data was acquired on a four-color flow cytometer and was analyzed by CellQuestPro software package. The percentages of different CD8+ cell subtypes (Tc1, Tc2 and Tc17) were quantified in CD8+ T lymphocytes. The comparison was made between LN+ versus LN- patients, as well as patients in different clinico-pathological status.
Results: The percentage of Tc1, Tc2 and Tc17 subsets were not significantly different between LN+ and LN- patients. Despite no difference in the percentages of Tc1 cells in LN+ patients with infiltrative ductal carcinoma (IDC), the mean expression of IFN-γ by Tc1 cells decreased significantly in comparison to LN- patients. On the other hand, the percentages of Tc2 and Tc17 effector subsets were increased in advanced stages (p=0.018 and p=0.009, respectively).
Conclusion: As the first study to investigate various effector subtypes of CD8+ lymphocytes in TDLNs of patients with breast cancer, our data collectively suggests a positive association between IL-17- and IL-4-producing CD8+ T cell percentages (Tc2 and Tc17) in TDLNs with breast cancer progression. Although the number of Tc1 cells seems not to be affected by cancer progression, down-regulation of IFN-γ by these cells seems to be associated with tumor metastasis to TDLNs. These findings may have implications in cancer immunotherapy based on CD8+ effector subsets.