title: Natural antibodies in human sera directed against blood-group-related determinants expressed on colon cancer cells.
abstract: Sera from 136 normal males and 33 members of families at high risk for colon cancer were tested for reactivity with six colon cancer cell lines by the protein A-mixed hemadsorption assay. Ninety-one sera had antibodies to colon cancer cell line HT-29. In 89 cases the antibodies were absorbed by human A and B erythrocytes or sheep erythrocytes. Antibodies in the remaining two sera, which were from sisters in the high-risk group, were not absorbed by red cells but could be absorbed by tumor cells expressing A or B blood-group determinants. Their reactivity was inhibited by some soluble blood-group glycoproteins. One serum (No. 4) was inhibited by A-active glycoproteins from human saliva and ovarian cyst fluids and from porcine mucosa, as well as by a polysaccharide derived from gastric cancer; it has an anti-A-like specificity. The other serum (No. 6) was inhibited by A and B glycoproteins, by a blood group precursor glycoprotein and by the same gastric cancer polysaccharide; it seems to have a wider specificity directed towards both A- and B-like structures. It is not known what caused production of these antibodies but it may be significant that they occurred in members of a family at high risk for developing colon cancer.
mesh_terms: D000042:Absorption; D000906:Antibodies / Q000032:analysis*; D000912:Antibodies, Neoplasm / Q000032:analysis*; D000954:Antigens, Surface / Q000276:immunology; D001789:Blood Group Antigens / Q000276:immunology*; D002460:Cell Line; D002478:Cells, Cultured; D003110:Colonic Neoplasms / Q000276:immunology*; D000939:Epitopes / Q000276:immunology*; D006801:Humans; D007417:Intestinal Polyps / Q000276:immunology; D008297:Male; D012306:Risk
chemical_list: D000906:Antibodies; D000912:Antibodies, Neoplasm; D000954:Antigens, Surface; D001789:Blood Group Antigens; D000939:Epitopes