The combined effect against colon-26 cells of heat treatment and immunization with heat treated colon-26 tumour cell extract

Cancer vaccines represent a promising new strategy for immunotherapy agains t cancer, but their effects are insufficiently understood. The effect of he at treatment against mouse colon adenocarcinoma cell line (colon-26), and c ombined effects of heat treatment and immunizing host animals with heat tre ated colon-26 cell extracts were investigated. Heat treatment of colon-26 c ells induced heat-shock protein 70 (HSP70), but not other HSP. Immunization of BALB/cJ mice with heat treated colon-26 cell extract, which was enriche d in HSP70, elicited antitumour immunity against subcutaneously injected co lon-26 cells. Furthermore, combination therapy of heat treatment and immuni zation with heat treated colon-26 cell extract significantly reduced tumour volumes compared with heat treatment alone. Similar immunization enhanced the cytotoxic activity of mouse splenic lymphocytes against untreated and h eat treated colon-26 cells in an in vitro assay, as well as against heat tr eated allogenic mouse lymphoma cell line (YAC-1). These findings suggest po ssible usefulness of heat treated cancer cell extract as a cancer vaccine, especially if given in combination with hyperthermia.