Serum mucin-associated antigen levels of cystic fibrosis patients are related to their ages and clinical statuses

Association between serum oncofetal antigens CA 19-9 and CA 125 and clinical status in patients with cystic fibrosis

In cystic fibrosis (CF), mucus plugging in the airways and in the gastrointestinal tract leads to severe morbidity and mortality. The mucin-associated antigens CA 19-9 and CA 125 are markers of gastrointestinal malignancy, and CA 19-9 has also been reported in association with pulmonary function in CF.

AIM

To test whether these antigens might serve as markers for the severity of pulmonary and gastrointestinal disease in CF.

METHODS

In 99 patients, aged 1 to 48 y, serum levels of CA 19-9 and CA 125 were measured by RIA and ELISA and related to clinical data.

RESULTS

Patients with severe mutations had significantly increased serum levels of CA 125, indicating an association with a more severe CF phenotype. This was further supported by the association with lung function, chronic pulmonary colonization of Pseudomonas aeruginosa and pancreatic insufficiency. CA 19-9 was also shown to be associated with lung function and Ps. aeruginosa colonization. No gastrointestinal malignancy was found in our patients despite very high values of CA 19-9 in some patients. During a 5-y follow-up, the very high serum levels of CA 19-9 decreased along with improved general condition of the patients.

CONCLUSION

Increased serum levels of CA 125 in CF patients were associated with severe cystic fibrosis transmembrane conductance regulator mutations and a severe phenotype. Both antigens were associated with pseudomonas colonization and lung function and CA 125 also with pancreatic insufficiency. The estimates of CA 19-9 are hampered by the influence of the Lewis histo-blood group system on the synthesis of CA 19-9.

Elevated levels of serum mucin-associated antigen in adult patients with cystic fibrosis

Previous studies using the CA 19-9 antibody have demonstrated that serum mucin levels in patients with cystic fibrosis (CF) are elevated and that the degree of elevation relates to the age of the patient and possibly to his or her clinical status. However, CA 19-9 only recognizes the mucin-associated blood group sialyl Le(a+) antigen, so mucin levels cannot be measured in patients without Lewis antigens. The present study used the 17B1 monoclonal antibody to measure serum mucin levels in normal subjects, and in patients with CF, patients with chronic obstructive pulmonary disease (COPD), and patients with lung transplants. Serum mucin levels were 25 ng/ml (+/- 1 SEM, n = 8) in normal subjects, 13,853 ng/ml (+/- 1,281, n = 25) in patients with CF, and 25.5 ng/ml (+/- 1.9, n = 17) in patients with COPD. Patients with CF who were sialyl Le(a-b-) also had elevated serum mucin levels (715 +/- 152, n = 2). Serum mucin levels of six lung transplant recipients with CF were elevated compared with those in normal subjects (4,621 +/- 765 ng/ml), but they were not different from serum mucin levels in six lung transplant recipients without CF (5,307 +/- 1.677 ng/ml). Preliminary characterization of the serum mucin antigen showed that: (1) in CF sera, the antigen is polydisperse and smaller than the antigen in normal sera; (2) the mucin antigen is distinct from ABO blood group antigens. Serum mucin levels may be a useful marker to follow a specific patient's response to therapy.

Chromatographic characterization of CA 19-9 molecules from cystic fibrosis and pancreatic carcinoma

We have compared the size, the binding to Concanavalin A (Con A), and the affinity for monoclonal antibody 1116NS-199 (Mab 19-9) among CA 19-9 molecules from sera of cystic fibrosis (CF) and pancreatic carcinoma patients and from sputum extracts. CA 19-9 molecules of two different sizes were found in all types of specimens by Sepharose 4B chromatography. While the smaller CA 19-9 molecule was predominant in CF patient sera, the larger molecule was associated with most of the sera from patients with pancreatic carcinoma. The majority of the sputum extracts contained the larger CA 19-9 molecule. All CA 19-9 molecules studied by Con A chromatography did not appear to bind to Con A, and almost 100% were found in the nonreactive fraction. The CA 19-9 molecules from sera of either CF or pancreatic carcinoma patients exhibited variable affinities for Mab 19-9, some approaching that of the standard curve but many also having lower affinities. The lowest affinity was displayed by CA 19-9 molecules from the sputum extract. It appears that development of more specific assays for CF and for carcinoma is possible if the correct CA 19-9 molecule is selected for antibody preparation and for use as standards.

Tumor markers CA 19-9 and CA 195 are also useful as markers for cystic fibrosis

When monoclonal kits are used we can no longer detect highly elevated serum concentrations of carcinoembryonic antigen in cystic fibrosis (CF) patients as we could earlier (Pediatr Res 10:223-236, 1975). Instead, we find increased concentrations of CA 19-9 or CA 195 in the CF sera. The serum levels of CA 19-9 not only reflect the pulmonary condition of CF patients but also respond well to antibiotic therapy. Several lines of evidence suggest that the elevated serum concentration of CA 19-9 is derived from sputum and corresponds with the amount of sputum in the lung. Correlations between CA 19-9 and CA 195 in random and serial specimens from both patients with CF and patients with pancreatic carcinoma suggest that all sera contain heterogeneous, Lewis blood group-related epitopes and the proportions of various epitopes are different among individual patients. When monitored on multiple tumor markers, the pattern of CF is different from that of pancreatic carcinoma although both usually show elevated CA 19-9. Our study indicates that both CA 19-9 and CA 195 can be used as sensitive markers for the early detection of exacerbation in CF patients.

Multiple potassium and chloride channels in the human colon carcinoma cell line SW1116

SW1116 cells have a profound capacity for secreting mucin molecules bearing the Lewisa epitope. Mucin molecules with the same epitope have been found to be elevated in the serum of patients with cystic fibrosis, a disease with defective ion channels. We therefore decided to study ion channels in this cell line. In the present work, we report the presence of two K(+)-channels and two Cl(-)-channels in the apical membrane of SW1116 cells. One of the K(+)-channels has a large conductance (approximately 278 pS), anomalous rectifying properties, and is inactivated rapidly. The second type exhibited a linear I/V curve (19 pS), was voltage insensitive and inactivation was not observed. In cell-attached patches, spontaneous openings of chloride channels were seen with higher frequency than previously reported in other colon carcinoma cell lines or airway epithelial cells. Inside-out experiments allowed identification of two different Cl(-)-channels (Cl(-)-1 and Cl(-)-2). Both exhibited rectification, but in opposite directions, and both were insensitive to NIPAB.

Additional fucosyl residues on membrane glycoproteins but not a secreted glycoprotein from cystic fibrosis fibroblasts

Glycopeptides derived from peripheral membrane glycoproteins of skin fibroblasts of seven patients with cystic fibrosis (CF) had an increase in fucosyl residues when compared with those of seven age, race and sex matched controls (Pediatr Res 1985;19:368-374). To further define these results, the membrane glycopeptides which bound to immobilized lentil lectin and thereby enriched in fucosyl residues linked alpha 1----6 to N-acetylglucosamine attached to asparagine, were Pronase digested, partially purified and examined by 500-MHz 1H-NMR spectroscopy. The CF derived glycopeptides had two different features when compared to those from Controls (1) an increased number of fucosyl residues linked alpha 1----6 to the N-acetylglucosamine attached to asparagine and (2) fucosyl residues linked alpha 1----3 to a branch N-acetylglucosamine. The glycopeptides from both sources were of the di and triantennary type containing sialic acid linked alpha 2----3 and alpha 2----6 to galactose in an approximate molar ratio of 3:2 and 2:1, from CF and Control, respectively. Glycopeptides derived from a glycoprotein, fibronectin, secreted from CF fibroblasts were also examined by 1H-NMR spectroscopy and showed no evidence of fucosyl residues linked alpha 1----3 to branch N-acetylglucosamine and a lesser percentage of core fucose than found in the peripheral membrane glycopeptides. These results define further the altered fucosylation of the CF peripheral membrane glycoproteins.

Isolation and characterization of mucin from the serum of cystic fibrosis patients

Using monoclonal antibody 19-9, elevated levels of the sialyl Lea antigen (NeuAc alpha 2-3Gal beta 1-3[Fuc alpha 1-4]GlcNac beta 1-3R) are detected in serum from most cystic fibrosis patients. We now report further characterization of the serum antigen and evidence that it is on a mucin glycoprotein and not on glycolipids. The antigen has an apparent molecular weight greater than 2 X 10(6) by gel filtration on Sephacryl S-400. On density gradient centrifugation, the antigen has a density of 1.54 g/ml in cesium chloride and 1.42 g/ml in cesium chloride/4 M guanidine HCl. Immunostaining with monoclonal antibody 19-9 of lipid extracts from cystic fibrosis patient serum and erythrocytes does not detect any antigen on glycolipids. The antigen was purified by gel filtration and density gradient centrifugation. After tritium labeling of the sialic acid residues, sodium dodecyl sulfate gel electrophoresis separates two subunits with apparent molecular weights of 200,000 and 400,000. All of the labeled sialic acid is released as low molecular weight oligosaccharides after mild alkaline borohydride degradation. The purified antigen contains fucose, galactosamine, glucosamine, and galactose but no mannose and is enriched in the amino acids threonine, serine, glycine, proline, and alanine. The purified antigen binds several antibodies recognizing epitopes common to many mucins. Thus, the physical, biochemical, and immunochemical properties of the purified antigen indicate that the sialyl Lea antigen is present on mucins in the serum of cystic fibrosis patients.