We investigated the effect of irradiation on the surface antigen expression of proto-oncogene c-erbB-2 on human adenocarcinoma cell lines. Cultured human colonic adenocarcinoma cell BM314 and gastric adenocarcinoma cells MKN45 were irradiated to investigate the expression of the Erb B-2 protein. Interferon-gamma (IFN-γ) was also used to treat these cancer cells. The expression of ErbB-2 showed remarkable increases on the surface of the membrane. Such upregulation was shown to be dose dependent, namely, higher radiation doses were associated with increased antigen expression. However, IFN-γ administ-ration did not show an increased expression of proto-oncogene c-erbB-2. These findings may explain partially the increased immunogenity of tumor cells following irradiation. The effect of irradiation is distinct from that of IFN-γ administration, suggesting that a different mechanism of action is present
