CD40 ligation thus could be used to sensitise a tumour to conventional treatment modalities such as chemo- or radiotherapy and additionally with a potential for stimulating natural immunity against solid tumours in the manner, which has already been seen in other malignancies both in vitro and in vivo (Eliopoulos et al, 1996; Bergamo et al, 1997; Dilloo et al, 1997; Kikuchi and Crystal, 1999). Here, CD40 is linked to neoplasm.