IL2 and neoplasm: Manipulating the immune system by interleukin-2 (IL-2) based immunotherapy may induce durable tumour regression in metastatic renal cell carcinoma (mRCC) (Minasian et al, 1993; Fyfe et al, 1995; Jeal and Goa, 1997; Bordin et al, 2000; Fisher et al, 2000; Negrier et al, 2000).