Functional expression of TRAIL by lymphoid and myeloid tumour cells.

TRAIL is a potent death protein that favours the killing of various types of cancer cells to normal cells, but under the right conditions TRAIL can also kill activated human T cells. TRAIL mRNA is widely expressed by normal cells but its expression by primary tumour cells is not known. In this study, primary tumour cells of haemopoietic origin constitutively expressed TRAIL mRNA and protein and were capable of inducing the apoptosis of target Jurkat cells in a dose-dependent manner. This killing effect was reversed by anti-TRAIL antibody. The functional expression of TRAIL by lymphoid and myeloid malignant cells raises the possibility of its involvement in tumour cell evasion of immunosurveillance, and could be related to spontaneous tumour cell death and necrosis.