IL6 and neoplasm: Several human tumour cell lines are known to produce IL-6 (Kawano et al, 1988; Miki et al, 1989; Meir et al, 1990; Siegall et al, 1990; Watson et al, 1990; Lee et al, 1992; Ohsaki et al, 1992; Takizawa et al, 1993; Oka et al, 1996).