TILs from seven consecutive tumours were cultured with GM-CSF (500 or 1000 nmol ml-1) without IL-2 supplementation, with suboptimal doses of IL-2 (8 and 40 U ml-1) plus GM-CSF (1000 nmol ml-1), and with a dose of IL-2 (400 U ml-1) which sufficed alone to induce TIL development plus GM-CSF (500 or 1000 nmol ml-1). Here, IL2 is linked to neoplasm.