[Pancreatic cancer-related antigen (PCAA) and pancreatic tissue antigen (PaA)--their chemical compositions, tissue localization, and clinical significance].
PCAA, a glycoprotein antigen identified and purified from ascited fluid of a pancreatic cancer patient and sharing the identical immunogenicity with Gelder's POA (Shimano, 1981) and PaA, a novel pancreas tissue antigen (Loor, 1981) purified from saline extract of human pancreas were studied. (1) Chemical composition: The purified PCAA from ascites fluid of a pancreatic cancer patient has a molecular weight of 10,000,000. The same antigenic substance as PCAA was also isolated and purified from normal colonic mucosa. Amino acid compositions of these antigens were similar. PCAA appeared to be a N-glycosidic glycoprotein. Antisera against these antigens were immunologically identical to Gelder's anti-POA in gel diffusion. The purified PaA has a molecular weight of 44,000, a sedimentation coefficient of 3.4S and an isoelectric point of 4.9. (2) Tissue localization: In pancreatic cancer tissues, PCAA and PaA were detected at apical cytoplasm of cancer cells, though positive cells were in different proportions and with different distribution each other. PCAA-positive cells were well differentiated while PaA-positive cells were less differentiated in histology. (3) Serum levels: A sensitive and reproducible sandwich-type enzyme immunosorbent assay has been developed for quantitation of PCAA and PaA. Using 18.6 micrograms/ml (mean + 2 S.D. of normal controls) as an upper limit, 43 of 76 pancreatic cancer (56%) and 34 of 167 other diseases (20%) had an elevated PCAA level. Using 21.5 ng/ml as an upper limit, 50 of 76 pancreatic cancer (66%) and 13 of 167 other diseases (8%) had an elevated PaA level. The sensitivity of simultaneous assay of PCAA and PaA for the detection of pancreatic cancer increased to be 90% (69/76) while false positive was 24% (40/167). The results indicate that combination assay of PCAA and PaA may be useful in immunodiagnosis of pancreatic cancer.
D000951:Antigens, Neoplasm / Q000032:analysis* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D010179:Pancreas / Q000276:immunology; D010190:Pancreatic Neoplasms / Q000276:immunology*; D014018:Tissue Distribution
D000951:Antigens, Neoplasm; C031192:oncofetal antigens; C019454:pancreas-specific antigen