Purification and characterisation of tumour necrosis factor-alpha with cytotoxic activity against AK-5 cells.

Tumour necrosis factor (TNF) has been purified from the sera of animals in which the rat histiocytoma AK-5, was rejected spontaneously. Purified TNF-alpha is cytotoxic to AK-5 cells in vitro and the cytotoxic activity of TNF is completely neutralized by anti TNF antiserum. The circulating TNF levels are high by day 10 after the tumour transplantation. Animals which do not regress the tumour have very low levels of TNF in serum. Production of TNF by tumour regressing animals is part of the host immune response to the AK-5 tumour. Also, spleenomegaly in the animals which reject the AK-5 tumour is observed.