The role of interferon gamma in the pathogenesis of Crohn's disease.

To investigate the role of interferon gamma in the pathogenesis of Crohn's disease, we examined the interferon gamma levels of serum, supernatant of cultured peripheral blood mononuclear cells activated by phytohemagglutinin, and medium of organ culture of colonic mucosa in Crohn's disease. Serum interferon gamma levels in Crohn's disease, especially in active or non-resected Crohn's disease, were more elevated than those in normal subjects. In contrast, the production of interferon gamma by peripheral blood mononuclear cells was reduced in Crohn's disease. In some patients, interferon gamma levels of organ culture medium of colonic mucosal tissue specimens were elevated. When peripheral blood mononuclear cells were preincubated for 72 hours, interferon gamma production in Crohn's disease increased from 23.8% to 62.3% in comparison to levels in healthy controls. These results indicate that elevated serum interferon gamma in Crohn's disease may originate from the intestine, and interferon gamma may be related to the immune reaction and inflammation in the intestine.