Increase of blood group A and loss of blood group Sda activity in the mucus from human neoplastic colon.

Aqueous extracts of human neoplastic and adjacent normal colonic mucosa were investigated for hemagglutination inhibition of both the anti-A serum and the Dolichos biflorus lectin. The anti-A antiserum was inhibited by the extracts from neoplastic tissues to a much higher extent than by that from normal mucosa; the inhibition was strictly dependent on the blood group and the secretor status of the individual. The inhibition titers against the Dolichos lectin were much lower for the tumor than for the normal tissue and the inhibition of this lectin was not dependent on blood group and secretor status. In addition, studies on the specificity of both agglutinins showed that only the anti-A antiserum reacted with the blood group A antigen in the colonic mucus whereas the Dolichos lectin reacted with a different substance which was not related to the blood group ABO system. The Dolichos reactive mucin was isolated by gel chromatography and by affinity chromatography on Dolichos-Sepharose. The partially purified mucin did not show any blood group A or H activity but reacted with all GalNAc specific lectins tested. A very high specific activity was obtained against the Dolichos biflorus lectin whereas the agglutinins from Salvia sclarea, Glycine max. (soybean) and Helix pomatia were less strongly inhibited no matter whether blood group A1, Tn, or Cad erythrocytes were used. By far the highest inhibitory activity was found against the human anti-Sd(a) antiserum regardless of whether the red blood cells were Cad or Sd(a+). By gel chromatography an equally pure mucin fraction could be obtained from neoplastic tissues which did not bind to either the anti-A antiserum nor the GalNAc specific lectins but could inhibit the anti-Sda antiserum at a far lower specific activity than the normal preparation.