Phenotypic characteristics of tumour-infiltrating lymphocytes in human oesophageal cancer tissues defined by quantitative two-colour analysis with flow-cytometry.

Phenotypic subpopulations of tumour-infiltrating lymphocytes (TIL) separated from human oesophageal cancer tissues were defined by quantitative two-colour analysis with flow-cytometry (FACScan), and their characteristics were investigated by comparison with peripheral blood lymphocytes (PBL) and intra-oesophageal lymphocytes from noncancerous tissue (IEL) as the controls. Fifteen patients (13 males and 2 females) with squamous cell carcinoma of the oesophagus were entered into the study. Lymphocytes were analyzed by FACScan and the frequencies of the subpopulations were determined using monoclonal antibodies for surface markers. Single colour analysis revealed a predominance of T cells among TIL and a significant reduction of natural killer (NK) cells compared with the controls. Two-colour analysis showed that CD4+ Leu8- (helper T cells) and CD8+ CD11b- (cytotoxic T cells) were significantly increased among TIL when compared with the controls. This significant increase of both helper and cytotoxic T cells, which are indispensable components of cellular immunity, strongly implies that TIL are performing a role in the expression of antigen-specific cellular immunity against the tumours. This is the first report of a phenotypic study of human oesophageal cancer that clearly indicates the significance of the TIL and suggests their potential for use as a source of adoptive immunotherapy.