Idiotype network systems are supposed to play important roles in regulation of the immune response. We applied anti-idiotypic(Id)monoclonal antibodies (MoAbs) to tumor associated antigen system to analyze idiotype networks and the internal image of antigen. Anti-Id MoAbs were developed to anti-CEA MoAb MA208 which reacted with peptide of CEA. One of the and-Id MoAbs, M7-625 could induce anti-anti-Id antibodies which reacted with antigen-CEA, suggesting that MoAb M7-625 serologically had the internal image of antigen. In order to confirm this point, the cloning experiment of M7-625 variable region was done. It showed that amino acid sequences of coplementary determining region (CDR) 2 and 3 of MoAb M7-625 heavy chain had the homology to those of CEA domain III. Furthermore, internal image-bearing anti-Id MoAb in ganglioside GM3 antigen system showed the vaccine effect against syngeneic B16 melanoma in C57/BL black mouse. These results suggest that internal image-bearing and-Id MoAbs are useful tools for cancer therapy.
