Lymphocyte subsets in tumour of patients with undifferentiated nasopharyngeal carcinoma: presence of lymphocytes with the phenotype of activated T cells.

We have analyzed lymphocytes infiltrating nasopharyngeal carcinomas, using a combination of immunoperoxidase staining of frozen and paraffin-embedded sections, and immunofluorescence on lymphocyte suspensions recovered from teased tumours. A panel of monoclonal antibodies was used to define lymphocytic subsets on frozen sections of 14 different tumours. The vast majority of peri- and intra-tumoral lymphocytes were stained by OKT3 antibody. In 8 sections, T4 positive cells were largely predominant, while T8 positive cells were the majority in three sections. Twenty-nine paraffin-embedded sections from other NPC patients stained with HNK-1 antibody showed a variable percentage of positive cells reaching 6 to 15% in nine patients. Most HNK-1 positive cells had the morphology of large granular lymphocytes typical of natural killer cells. Double staining experiments on lymphocytes isolated from 7 tumours revealed a constant presence of T3 positive, HLA-DR positive lymphocytes (from 6 to 29% of mononuclear cells), and of lymphocytes coexpressing the T3 and the Tac (IL-2 receptor) antigens (from 5 to 12% of mononuclear cells). Lymphocytes with a phenotype of activated T-cells are thus constantly found in NPC tumours.