The effect of proctocolectomy on serum antibody levels against cow's milk proteins in patients with chronic ulcerative colitis, with special reference to liver changes.

BACKGROUND

The levels of antibodies against cow's milk proteins in ulcerative colitis (UC) were used to study whether mucosal inflammation leads to immune recognition, as a marker of enhanced permeability, of dietary proteins. A further purpose was to study the effect of proctocolectomy on the serum antibody levels against cow's milk proteins and their relation to biochemical and histologic liver abnormalities associated with ulcerative colitis.

METHODS

Serum antibody levels against six cow's milk proteins, alpha-casein, alpha-lactalbumin (LA), beta-lactoglobulin A (LGA), beta-lactoglobulin B (LGB), bovine serum albumin (BSA), and whole milk powder (MP) were determined before and after (mean, 24 months) proctocolectomy in 15 patients with ulcerative colitis. Simultaneously, serum liver enzymes were analyzed. A liver biopsy specimen was also obtained at proctocolectomy.

RESULTS

Before proctocolectomy IgA antibody levels were significantly increased against all antigens except BSA. Increased levels of IgM antibodies against LGA, LGB, and BSA were also detected. IgG antibodies were significantly increased only against LGA. After proctocolectomy IgA and IgM antibody levels decreased significantly (p < 0.05) against LGA, LGB, and LA, whereas IgG antibodies increased significantly (p < 0.01). In the patient group with abnormal liver histology (n = 9) the IgA antibodies to all cow's milk proteins were significantly higher (p < 0.02) than in the group with normal liver histology both before and after proctocolectomy. The IgA antibody levels showed a significant positive correlation with alanine amino-transferase and gamma-glutamyltransferase (r value from 0.460 to 0.721, p value from < 0.05 to < 0.01), but not with alkaline phosphatase.

CONCLUSIONS

These results suggest that the inflamed mucosa in UC allows the antigenic contents of the bowel to escape. Proctocolectomy alters the antibody levels against certain milk proteins, which may serve as a model to suggest that proctocolectomy, probably by eliminating inflammation, may have positive effects by reducing the foreign pathogenic antigen and immune complex load.