Purification of tumor-associated embryonic substance from mouse ascites tumor cells: its cross-reactivity with human CEA.
1. Tumor-associated embryonic substance (TAES), which was detected on MM2 cells by cell agglutination method using MM2-regressor mouse serum, was purified from MM2 cells to gel electrophoretically pure substance. The recovery was 0.9 mg (protein) from 100 g (wet weight) cells. TAES is a glycoprotein of 21S. 2. TAES inhibited cross-agglutination of MM2 cells by various syngeneic regressor serum, tumor-bearer serum or pregnant mouse serum. 3. From agglutination inhibition experiment, it was concluded that TAES and human CEA have a common binding site for the agglutination factor. 4. The binding site contains saccharide moiety of these molecules with N-acetyl glucosamine at the non-reducing terminus. 5. Although TAES and CEA cross-reacted in agglutination-inhibition experiments, their antigenicity to xenogeneic animal did not show cross-reactivity.