Mechanisms involved in natural killer cell mediated target cell death leading to spontaneous tumour regression
We have studied the mechanisms involved in the spontaneous regression of a rat histiocytoma in syngeneic hosts and tumour cell death processes. In addition to the natural killer (NK) cells which act through antibody dependent cellular cytotoxicity (ADCC), TNF-α also participates in the induction of necrosis in tumours. We have shown that the tumour cell is killed by necrosis which is perforce mediated, and apoptosis leading to target cell DNA fragmentation. A prior activation of the effector cells is essential before it can kill the target cell, as naive effector cells are ineffective. Activation of effector cells is mediated by Thl type of cytokinesin viro andin vivo. IFN-γ seems to play an important role in tumour regression as injection of antibodies to IFN-γin vivo inhibited tumour rejection.