IFNG and neoplasm: We also repeatedly reported that peptide-stimulated PBMCs from certain healthy donors produced significant levels of IFN-γ in response to peptides, but rarely showed cytotoxicity against tumour cells in an HLA-A24 or -A2 restricted manner by means of a 51Cr-release assay (Harashima et al, 2001; Ito et al, 2000, 2001; Kawano et al, 2000; Nishizaka et al, 2000).