Serological studies in Crohn's disease.

ELISA and immunofluorescence tests were carried out on sera from patients with Crohn's disease and ulcerative colitis. The results indicate that mean antibody levels to Yersinia enterocolitica types O:9 and O:3 and Klebsiella pneumoniae, but not Pseudomonas maltophilia, are significantly higher in these patients than in control subjects. There are differing antibody levels in ileal and colonic disease, and there is a significant fall in antibody levels 9-12 months after remission from clinical symptoms in patients providing serial serum samples. However, there is no correlation between the severity of the disease and antibody titres.