FOXP3 and nasopharyngeal carcinoma: We also found IL-17-secreting T clones highly expressing Foxp3, and with the suppression function to naïve T cells from NPC TIL in vitro (unpublished data), the failure to find the double IL-17 and Foxp3 positive TIL in NPC may be due to the lack of sensitivity of the IHC staining method or the differences between in vivo and in vitro conditions.