“…Fresh tumour cells from human neoplastic tissues are generally resistant to natural cytotoxicity as measured by conventional cytolysis assays (Pattengale et al, 1982;Serrate et al, 1982;Vanky et al, 1980;Verkmeister et al, 1979;Vose et al, 1977aVose et al, , 1977bVose et al, , 1978Vose & Moore, 1980;Zarling et al, 1979). In a study with various human tumours, mainly of mesenchymal origin, Vanky et al reported that IFN-induced killing of fresh biopsy cells only if allogeneic combinations of PBL and target cells were used (Vanky et al, 1980).…”