title: Complement-dependent lysis of Erhlich ascites tumor cells by human serum (ascitolysin) is lowered in cancer patients and raised in pregnant women.
abstract: Normal human serum has been shown to contain IgM antibodies that are lytic to Ehrlich ascites tumor cells in the presence of complement. We call this activity ascitolysin (AL). Using a 51Cr release assay, the AL titers of 164 normal sera, 211 sera from patients with non-malignant disease, 62 sera from 25 pregnant women and 170 sera from cancer patients were estimated. The patient sera were taken preoperatively, and were assigned to the cancer or non-cancer group after histological diagnosis. In normals, higher titers were found in sera of A and O blood groups but not B and AB. The difference was due to a fraction absorbed by B red blood cells. Sera from untreated cancer patients showed significantly reduced titers when compared to normal, benign tumor, chronic and other non-malignant disease groups. In pregnancy, titers were positively correlated with duration and remained elevated for at least 6 weeks post partum. About 30% of AL activity was absorbed by the free galactose groups of agarose. This fraction was significantly lower in untreated cancer patients. Anti-T antigen antibodies do not contribute to AL levels. Galactophilic blocking factors were also found; eight times more frequently in cancer sera than in normals. The non-absorbed fraction was also lower in cancer sera. The data suggest that AL antibodies may be directed against human oncofetal antigens.
mesh_terms: D000017:ABO Blood-Group System; D000328:Adult; D000367:Age Factors; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001667:Binding, Competitive; D002286:Carcinoma, Ehrlich Tumor / Q000276:immunology*; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000276:immunology*; D003603:Cytotoxins / Q000276:immunology*; D005260:Female; D005690:Galactose / Q000276:immunology; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D012685:Sepharose / Q000276:immunology; D012737:Sex Factors; D013997:Time Factors
chemical_list: D000017:ABO Blood-Group System; D000906:Antibodies; D003603:Cytotoxins; D007075:Immunoglobulin M; D003165:Complement System Proteins; D012685:Sepharose; D005690:Galactose