Increased production of interferon-gamma by tumour infiltrating T lymphocytes in nasopharyngeal carcinoma: indicative of an activated status

Undifferentiated nasopharyngeal carcinomas (UNPC) are characterised by an a ssociation with Epstein-Barr virus and an abundant lymphoid stroma. We stud ied the functional status of the infiltrating T cells in ten UNPC biopsies using an immunohistochemical approach. Twelve non-NPC biopsies were include d as controls. Tumour cells of UNPC were positive for HLA class I(10/10) an d II (8/10), LMP1 (3/10), and CD86 (6/10). Tumour infiltrating T cells (TIL s) were detected with antibodies directed at CD3, CD4, and CD8, and shown t o be comparable to that in the control biopsies. Although expression of CD2 8 was shown to be decreased in TILs, expression of CD25 and IFN-gamma at a relatively high percentage could be consistently detected in the UNPC biops ies. These data suggest that TILs in UNPC are in an activated status, and t his T cell response is possibly directed at the tumour cells. (C) 1999 Else vier Science Ireland Ltd. All rights reserved.