Crohn's disease and mycobacteria: two cases of Crohn's disease with high anti-mycobacterial antibody levels cured by dapsone therapy.

Five patients with Crohn's colitis or ileocolitis (CD) refractory to conventional therapy were enrolled in an open trial with dapsone (100 mg/day). This therapy was apparently effective in two out of five patients. In these patients we observed a clinical improvement after one month of therapy and, in the first patient, a complete healing of all the cutaneous and rectal ulcers. In the two responders antibody levels to a soluble extract of M. paratuberculosis (MPSE) were significantly greater than in the three non-responders (P = 0.03); in the first patient, moreover, there was a rise of 39% in antibody titres following the treatment. This rise in antibody levels, that might be expected following death of the pathogen and release of antigen, is similar to that observed after treatment of tuberculosis. Our data suggest that a mycobacterial species or another pathogen that cross-react with those of MPSE, sensitive to dapsone, may in a subset of cases be responsible for the development of CD. This is the first report of clinical cure with an agent active against specific bacterial species, associated with immunologic confirmation of a response.