Serum antibodies to Escherichia coli in subjects with ulcerative colitis.
It has been proposed that in ulcerative colitis the intestinal flora stimulates autoimmune reactions to colonic epithelium through shared specificities exposed in a `common antigen' found in most Enterobacteriaceae. The present experiments aimed to resolve conflicting data as to whether patients with ulcerative colitis have selectively increased serum antibody titres to enterobacterial common antigen or E. coli 014, which is rich in enterobacterial common antigen. Antibody titres to enterobacterial common antigen and lipopolysaccharides of E. coli 014 and of five serotypes of E. coli which occur frequently in human faeces were measured by passive haemagglutination. Sera were obtained from patients with ulcerative colitis, age- and sex-matched controls and subjects with other gastrointestinal disorders. Serum titres to enterobacterial common antigen and E. coli 014 lipopolysaccharide were not increased significantly in subjects with ulcerative colitis but significant increases were observed in subjects with chronic liver disease without colitis. Patients with active ulcerative colitis, patients with chronic liver disease and subjects convalescent from Salmonella or Shigella infections all had significantly increased serum titres to the antigens as a group. Class-specific enhancement of passive haemagglutination indicated that the class distribution of serum antibodies was similar in subjects with ulcerative colitis and controls.