Conclusion
TDLNs and metastatic LNs are characterized by a high accumulation of Tregs expressing high levels of CTLA-4 and PD-1. High infiltration of Tregs can be a potential driver of an immunosuppressive milieu in TDLNs that can, in turn, favour cancer progression. High accumulation of Tregs expressing CTLA-4 and PD-1 in TDLNs is associated with lymph node involvement, but not with the size of the primary tumour.
Methods
Samples including TDLNs, non-TDLNs and metastatic lymph nodes (LNs) from 23 patients with oral squamous cell carcinoma (OSCC) were analyzed by multicolour flow cytometry with a focus on Tregs population and expression of CTLA-4 and PD-1.
Results
TDLNs and metastatic LNs were characterized by a significantly higher infiltration of Tregs defined as CD4+FoxP3+CD25highCD127low cells and significantly higher expression of CTLA-4 and PD-1 on Tregs compared with non-TDLNs. Tregs in TDLNs and metastatic LNs co-expressed CTLA-4 and PD-1 abundantly. High expression of these immune check-point molecules correlated with positive N-stage but not with T-stage.