ABSTRACT
CTL responses by autologous colorectal cancer cells were observed in five cases. The specific CTL was induced from two cases, in which tumor associated antigen, CA-Hb_3, was strongly positive. The CTL could not induced from other three cases in which CA-Hb_3 antigen was weakly positive. Weakly positive tumor cells in the three cases were loaded CA-Hb_3 antigen into cytoplasmas by the cationic liposomes and tested by immunohistochemical assay. The results showed that CA-Hb_3 antigen of tumor cells in two cases changed to strongly positive, and could induce CTL responses successfully. With blocking agents BFA and anti-MHC-I monoclonal antibody, CTL responses could be blocked. Our results suggested that soluble CA-Hb_3 antigen could enhance the immunogenity of colorectal cancer cells and induce effective anti-tumor cellular immune responses.