Serum Antibodies to Mycobacterium paratuberculosis in Patients with Crohn's Disease

Mycobacterium paratuberculosis has beensuggested as a causative organism of Crohn's disease.Despite a long-term debate to prove this possibility,the role of this bacteria in the pathogenesis of Crohn's disease is still a subject of controversy. Inthe present study, serum antibodies (IgG, IgA, and IgM)to the protoplasmic antigen of M. paratuberculosis werequantified in patients with Crohn's disease and in control subjects by using anenzyme-linked immunosorbent assay whose specificity wasincreased by preabsorbing the sera with cell extracts ofMycobacterium phlei . As compared to normal controls (1/20; 0.062 ± 0.022), a significantdifference was seen in the antibody-positive prevalencerate and mean values of the serum IgG titer in patientswith Crohn's disease (5/13; 0.102 ± 0.039) (P< 0.05), but not in patients with ulcerativecolitis (2/20; 0.065 ± 0.035) and tuberculosis(0/4; 0.053 ± 0.008). No significant differenceswere seen in the antibody-positive prevalence rate andmean values of the serum IgA and IgM titers amongthe four study groups. These results indicate the uniqueimmune response to M. paratuberculosis in patients withCrohn's disease, suggesting that this organism may play some role in the pathogenesis ofCrohn's disease.