“…Monocyte-mediated cytotoxicity depends on expression and biological activity of TNF. TNF may be secreted or exert tumouricidal activity following transmembrane expression (Philip & Epstein, 1986;Kriegler et al, 1988;Luettig et al, 1989;Wing et al, 1989;Peck et al, 1989Peck et al, , 1991Perez et al, 1990;Bernasconi et al, 1991;Woods & Chapes, 1993;van de Loosedrecht et al, 1993;Higuchi & Aggarwal, 1994). Transmembrane TNF mediates tumour cell apoptosis following direct contact of the effector cell and target cell (Cannistra et al, 1988;Kriegler et al, 1988;Perez et al, 1990;Bernasconi et al, 1991).…”