Biliary mucin secreted by cultured human gallbladder epithelial cells carries the epitope of CA 19-9.
Serum CA 19-9 is increased in patients with different gastrointestinal malignancies. Unfortunately, CA 19-9 is also detected in high concentrations in normal bile causing unspecific serum elevations during inflammatory disease of the biliary tract and cholestasis. In order to identify the source of CA 19-9 in bile, the capacity of cultured human gallbladder epithelial cells (HGBEC) to secrete CA 19-9 was investigated. Cells were harvested from gallbladders removed by cholecystectomy and cultured for up to 14 days in collagen I coated 24-well culture dishes. CA 19-9 was measured in the culture medium by a solid-phase CA 19-9 EIA (Boehringer). In addition, culture medium was separated by Sepharose 4B-Cl, Concanavalin-A (Con-A) and CA 19-9 affinity chromatography. Significant CA 19-9 activity was measured in the culture medium after a 24 hour incubation period. Following separation of the culture medium by Sepharose 4B-Cl and Con-A affinity chromatography, 90% of the CA 19-9 activity was recovered in the exclusion volume (> 2000 kDa) from which 90% were identified as Con-A negative. A close correlation was found between CA 19-9 and concentrations of mucin purified from human gallbladder bile. Furthermore, CA 19-9 affinity chromatography selectively extracted mucins from the culture medium of HGBEC. Finally, addition of the mucin secretagogue bethanechol (6 mM) to the culture medium increased CA 19-9 activity in the medium. In conclusion, normal HGBEC secrete mucins carrying the epitope of CA 19-9. During inflammatory biliary disease unspecific elevation of CA 19-9 in serum may reflect both inflammatory hypersecretion and leakage of biliary mucins into serum.
von Ritter
C
C
Department of Medicine II, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
Eder
M I
MI
Stieber
P
P
Lamerz
R
R
Jüngst
D
D
Strigl
M
M
Meyer
G
G
Reuter
C
C
Paumgartner
G
G
D018723:Bethanechol / Q000494:pharmacology; D001646:Bile / Q000737:chemistry*; D018395:CA-19-9 Antigen / Q000032:analysis*; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D002846:Chromatography, Affinity; D004848:Epithelium / Q000378:metabolism; D005704:Gallbladder / Q000378:metabolism*; D006801:Humans; D009077:Mucins / Q000032:analysis*
D018395:CA-19-9 Antigen; D009077:Mucins; D018723:Bethanechol