Effect of food intake on circulating antigen-antibody complexes in patients with alcoholic liver cirrhosis

Circulating antibodies to Saccharomyces cerevisiae (bakers'/brewers' yeast) in gastrointestinal disease

AIM

To measure circulating antibodies to yeast organisms that could be used to characterise the yeast specific immune response in gastrointestinal disease.

METHODS

A quantitative, isotype specific enzyme linked immunosorbent assay was developed to measure circulating antibodies to an aqueous extract of Saccharomyces cerevisiae (sacc). Comparisons of specific antibody concentrations were made between 224 healthy controls and 51 patients with Crohn's disease, 41 with ulcerative colitis, 24 with indeterminate colitis, 23 with chronic liver disease, 17 with coeliac disease, and seven with irritable bowel syndrome. Additional comparisons were made between Crohn's disease and ulcerative colitis patients. Within the Crohn's disease group, the dependence of antibody levels on several clinical variables was assessed.

RESULTS

IgG and IgA anti-sacc antibodies were significantly raised in Crohn's disease. IgG antibodies were also raised in patients with chronic liver disease. Among patients with Crohn's disease, IgG antibody concentrations were higher in those with serum alpha 1 acid glycoprotein (AAG) above the normal range and there was a strong trend towards increased IgG anti-sacc in the presence of small bowel disease, whereas IgA anti-sacc correlated positively with disease duration. No differences were detected according to whether patients were taking steroids. Neither the Crohn's disease nor the chronic liver disease group differed from normal subjects in respect of IgG antibodies to bovine milk casein. On linear regression analysis of complete data from 39 Crohn's disease patients, AAG was found to be a significant predictor of both IgG and IgA antibodies, and male sex and disease duration to be additional predictors of IgA antibodies. There was a significant difference in IgG antibodies between Crohn's disease and ulcerative colitis.

CONCLUSIONS

Raised antibodies to yeast, although not completely specific for Crohn's disease, may have a future role in diagnosis. The assays described here could be used to address this question in the context of a prospective study.

Response of circulating immune complexes to food challenge in relapsing IgA nephropathy

The response of circulating immune complexes (CIC) to food challenge was assessed in 15 subjects with IgA nephropathy (IgAN) and recurrent macroscopic haematuria. CIC were measured by solid-phase C1q binding assay (SP-C1q), immunoglobulin class-specific polyethylene glycol (PEG) precipitation assays (PEG-G, PEG-A, PEG-M) and by an antigen (ovalbumin)-specific radioimmunoassay after acid dissociation (OA-IC). CIC were measured when the subjects were fasting and hourly for 6 h after a test meal containing eggs. All 15 subjects were tested while clinically quiescent (remission) and 6 were tested again during episodes of macroscopic haematuria (relapse). The PEG-A CIC response to food challenge was significantly exaggerated in IgAN remission compared with controls at 3-6 h after food. There were also non-significant increases in PEG-G, though not in PEG-M. Paired data showed further exaggeration of PEG-G, PEG-A and PEG-M responses to food during IgAN relapse, but significance was not attained if the findings in 1 subject were separated. In this individual a florid clinical relapse with transient decline in renal function was associated with very high levels of PEG-IC, and only in this patient in relapse was OA-IC detectable, confirming that some PEG-precipitated material represented antigen-antibody complexes containing food antigen.

Monoclonal antibodies to distinct epitopes on human IgA and their use to IgA determination

Several monoclonal antibodies (MAbs) against human IgA have been obtained which specifically bind to human myeloma and polyclonal IgA. Three of these MAbs have been purified and studied further. They recognize both IgA subclasses and define three distinct epitopes on the IgA molecule. These MAbs were used to develop a solid-phase radioimmunoassay (RIA) in which one MAb was immobilized and the other two were labeled with 125I. The assay has a sensitivity in the nanogram range. A good correlation was found (r = 0.97, P less than 0.001) when the solid-phase RIA was compared with a commercially available immunodiffusion technique for the determination of IgA levels in serum samples.

[Alcohol and IgA in the kidney]

Patients with chronic alcoholic liver disease show an increase in serum IgA with a preferential elevation of polymeric IgA. Furthermore, immune complexes containing IgA can be demonstrated. These changes may be explained by an alcohol-induced increase in intestinal permeability to macromolecular antigens leading to an IgA response, and by a decreased hepatic clearance of polymeric IgA not dependent on a secretory component. The prevalence of glomerular IgA deposits amounts to 50% in patients with alcoholic cirrhosis examined at autopsy. Polymeric and monomeric IgA, partially as immune complexes can be detected. However, urinary symptoms very rarely occur. The factors leading to glomerulonephritis following IgA deposition are poorly understood.

Increased serum antibody levels against cow's milk proteins in children with chronic liver disease

We measured IgG, IgM and IgA antibodies to cow's milk proteins: alpha-casein, alpha-lactalbumin, bovine serum albumin, beta-lactoglobulin-a and beta-lactoglobulin-b in the sera of 29 pediatric patients with liver disease. IgG antibodies to bovine serum albumin, beta-lactoglobulin-a and beta-lactoglobulin-b and IgA antibodies to alpha-casein were elevated in most of the patients compared to age-matched controls. We postulate that, in patients with liver disease either increased intestinal uptake resulting in increased humoral response, or decreased hepatic clearance of food antigens intensifying a humoral response to these foreign antigens, may occur.

Anti-albumin antibodies in sera of patients with liver disease

We used passive haemagglutination assay to examine sera from 77 patients with various liver diseases for the presence of antibodies to human serum albumin (HSA), bovine serum albumin (BSA) ans ovalbumin (OA). The antibody titre to BSA was higher than that to OA or HSA. Of the examined diseases, in chronic active hepatitis and liver cirrhosis, the titre and incidence of anti-BSA antibody were highest. There was a positive correlation between anti-BSA antibody and serum gamma-globulin level. Sephadex G-200 column chromatography and immunoelectrophoresis revealed that the anti-BSA antibody belonged to the IgM class.

Titres of antibodies to gut-derived antigens in patients with chronic schistosomiasis mansoni

Serum titres of antibodies against six intestinal, one ubiquitous and one non-intestinal bacteria were determined in patients with severe hepatosplenic schistosomiasis mansoni, with light intestinal schistosomiasis and in normal subjects. No significant difference was observed among the three groups of subjects for levels of antibodies against two non-intestinal bacteria and four of the intestinal bacteria. Patients with hepatosplenic schistosomiasis had titres of antibodies against one strain of Pseudomonas aeruginosa and one strain of Escherichia coli lower than those observed in other groups of subjects. Despite the partial obliteration of the hepatic blood outflow and the elevated portal pressure, hepatic clearance of the portal blood is efficient in chronic human schistosomiasis, and unlike alcoholic liver cirrhosis, avoids excessive stimulation of the immune system by a gut-derived antigens.

Measurement of glycoprotein content and cell kinetics in preulcerous gastric mucosa

In an attempt to evaluate the role of gastric mucosal defense factors in ulcerogenesis, we measured the levels of glycoproteins in the mucosa as well as mucosal cell turnover in the preulcerous phase and compared these parameters to the normal mucosa in the same animal. Ovalbumin-presensitized Praomys (Mastomys) natalensis were challenged in the gastric wall with ovalbumin and a gastric ulcer developed at the challenge site 3 days later as a result of a mucosal anaphylactic reaction. This model enabled us to study the events occurring at the site of a future ulceration. Gas-liquid chromatographic determination of mucosal glycoproteins showed that the normal and preulcerous mucosae had similar levels. Cell turnover, determined by [3H]thymidine incorporation, was stimulated as a result of the preulcerous anaphylactic reaction at 24 hours postchallenge whereas at 48 hours the values were not different from those obtained in controls. These results suggest that the pathogenesis of anaphylactic gastric ulcer involves a change in cell turnover but no changes in the production of gastric mucus.