Antibody to carcinoembryonic antigen in hamsters bearing GW-39 human tumors.

The appearance of anti-carcinoembryonic antigen (CEA) activity in the sera of hamsters bearing i.m. heterografts of GW-39, a CEA-producing colonic tumor of human origin, was demonstrated in radioimmunoassay using radioiodinated CEA purified from GW-39. Column chromatography, sucrose gradient ultracentrifugation, and radioimmunoelectrophoresis of pooled sera from tumor-bearing hamsters showed that the CEA antibody was of the immunoglobulin M type. The CEA antibody in tumor sera contained two specificities that reacted with different determinants on the CEA. On specificity reacted with a blood group-related determinant, whereas the remaining specificity was against a unique site on the CEA. Sequential analysis of individual tumor-bearing animals revealed that an increase in tumor growth paralleled the concomitant appearance of circulating CEA and highest antibody titer, suggesting that immunoglobulin M antibody, antigen, or complexes thereof influence tumor growth in this model.