Comparative studies on immunoglobulins, complement component (C3), albumin, and immunoglobulin A-containing circulating immune complexes in serum and bile of patients with biliary obstruction

Cholestasis is the Main Determinant of Abnormal CA 19–9 Levels in Patients with Liver Cirrhosis

Background/Aims

Altered CA19–9 levels are commonly found in patients with liver cirrhosis though a clear explanation for this finding has not yet been given. The aim of this study was to investigate whether CA19–9 levels might be related to alterations in biochemical parameters and/or to functional impairment in cirrhotic patients with and without hepatocellular carcinoma. Methods: We studied 126 patients with liver cirrhosis, 60 of whom also had hepatocellular carcinoma. CA19–9 values were related to clinical, biochemical and functional parameters. In half of the patients CA19–9 levels were related to the monoethylglycinexylidide test, which is a dynamic liver function test.

Results

In more than half the cases CA19–9 values were above the upper limit. Liver function worsening as assessed by Child-Pugh's score and monoethylglycinexylidide test did not seem to influence the alteration of the marker. By contrast, in univariate analysis CA19–9 correlated with aminotransferases, γ-glutamyltransferase and alkaline phosphatase. Multivariate analysis showed that besides alkaline phosphatase also the presence of hepatocellular carcinoma might influence the alteration of CA19–9, although the marker was of no use for the diagnosis of liver cancer in patients with altered though not diagnostic α-fetoprotein levels.

Conclusions

In our study we confirmed the correlation of CA19–9 levels with cholestasis and cytolysis parameters. Moreover, we found no association between CA19–9 levels and impaired liver function as assessed by means of the Child-Pugh's score and the monoethylglycinexylidide test, which is cholestasis-independent and explores liver metabolic and clearance activities. The cholestatic picture that characterizes liver cirrhosis might enhance the expression and passage of the marker from the bile to the blood. The addition of CA19–9 assessment is not useful for the diagnosis of hepatocellular carcinoma in patients with non-diagnostic levels of α-fetoprotein. Caution should therefore be used when evaluating CA19–9 in cirrhotic patients with cholestasis, since false positive results may occur.

Characterization of complement C3, C4, and factor B molecules in human bile

We performed molecular analysis of complement components (C3, C4, and factor B) in human bile by sodium dodecyl sulfate-polyarylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Complement C3 was detected as a molecule composed of a 115-kDa alpha-chain linked to a 70-kDa beta-chain by disulfide bonds, and C3 levels ranged from 45 to 650 micrograms/ml (n = 15). C4 was detected as a triple chain (98-kDa alpha-chain, 73-kDa beta-chain, and 33-kDa gamma-chain) molecule linked by disulfide bonds, and C4 levels ranged from 2.5 to 60 micrograms/ml. Factor B, a component of the alternative pathway, was also detected, as an intact form. Factor B levels ranged from 0.3 to 8.0 micrograms/ml. The sizes and subunit structures of complement components in human bile were compatible with those reported in human serum. The results of a hemolytic assay indicated that complement molecules in human bile were functionally active. These molecules may participate in local immune and inflammatory responses in the biliary tract.

Tumour necrosis factor-alpha up-regulates decay-accelerating factor gene expression in human intestinal epithelial cells

The increased expression of decay-accelerating factor (DAF) has been detected in intestinal epithelial cells at the inflamed mucosa. In this study, we examined the effects of tumour necrosis factor (TNF)-alpha on DAF expression in three intestinal epithelial cell lines. DAF mRNA expression was evaluated by Northern blot analysis, and DAF protein expression was analysed by biotin labelling and immunoprecipitation. TNF-alpha induced a marked increase in DAF mRNA and protein expression in HT-29, T84 and Caco-2 cells. In HT-29 cells, the effects of TNF-a on DAF mRNA accumulation were observed in a dose-dependent manner; DAF mRNA accumulation reached a maximum at 3-6 hr, and then gradually decreased. These effects of TNF-alpha required de novo protein synthesis. Messenger RNA stability studies suggested that TNF-alpha partially regulated DAF gene expression by a posttranscriptional mechanism. Moreover, the combination of TNF-alpha and interleukin (IL)-4 induced an additive increase in DAF mRNA accumulation in HT-29 and T84 cells. In human intestinal epithelial cells, TNF-alpha acts as a potent inducer of DAF mRNA expression, indicating an important role for TNF-alpha in the regulation of DAF expression at the inflamed mucosa.

Experimental foreign-body infection in the biliary tract in rats

BACKGROUND

Biomaterials used for biliary drainage may potentially result in biomaterial-associated infections.

METHODS

Foreign-body infection in the biliary tract was investigated in rats. Rubber drain pieces were implanted in the biliary tract in rats for 1-4 weeks, followed by challenges with 10(2) to 10(4) colony-forming units (cfu) Escherichia coli injected into the common bile duct. The rate of infection was calculated, the bacterial growth in the biliary tract was observed over 72 h after challenges, and the opsonic activity in bile and in sera was assessed.

RESULTS

In the group with drain material, inocula as small as 10(2) cfu produced persisting infection in the common bile duct in 90% of animals, whereas the same number of E. coli infected only 30% of rats in the control and sham implantation groups (p < 0.01, chi-square test). Complement-mediated opsonic activity in bile of animals with implanted drain pieces gradually decreased with time, whereas opsonic activity in sera from the same animals remained unchanged.

CONCLUSIONS

Implants in the biliary tract impair local host defense, resulting in an increased susceptibility to microbial infection.

Effects of percutaneous transhepatic biliary drainage on blood-bile permeability and selective IgA transport in patients with biliary obstructions

Biliary obstruction induces a increase in the permeability between blood and bile, and a decrease in the rate of immunoglobulin A (IgA) transport into bile. We investigated the effects of percutaneous transhepatic biliary drainage (PTBD) on these derangements. PTBD reduced the extent of elevation of the bile-to-serum ratio of Immunoglobulin G (IgG; IgG-BS ratio) in patients with obstructive jaundice. Because IgG is known to be passively transported from serum to bile, the results indicate that PTBD restores the blood-bile barrier function. The IgA-BS ratio/IgG-BS ratio index (IgA/IgG index) and the IgM/IgG index, which indicated the function of selective transport of IgA and IgM into bile, initially decreased and then returned to the normal range 17 days after PTBD in patients who experienced a rapid resolution of hyperbilirubinemia. However these indices remained low in patients who did not experience this resolution. The serum secretory IgA levels in patients who did not experienced rapid resolution of hyperbilirubinemia markedly increased before PTBD. The serum secretory IgA levels in the patients who did and those who did not experience rapid resolution of hyperbilirubinemia, after initially increasing, decreased after PTBD. However the level returned to the control range only in patients who experienced a rapid resolution. These results indicate that the secretory IgA level is a sensitive indicator of hepatobiliary function, and measurement of the level of secretory IgA could predict the effect of PTBD.