Serum interferon activity in inflammatory bowel disease

Serum interferon (IFN) of-class was studied in 64 consecutive patients, 26 with Crohn's disease, 38 with ulcerative colitis, and in 34 healthy volunteers. Detectable IFN- in 10 patients was associated with a moderate to severe activity of chronic inflammatory bowel disease (CIBD). However, 19 of 28 patients (68%) with activity in their disease did not have elevated IFN- levels. The three groups, ulcerative colitis, Crohn's disease, and healthy volunteers did not reveal any statistically significant difference in serum IFN-, as four of 34 healthy controls without intercurrent infections had elevated levels as well. Possible effects of, , and classes of IFN on endogenous arachidonic acid (AA) release and metabolism in human neutrophils was investigated in a substudy. IFN- caused a dose-dependent release of AA from phospholipids and metabolism of a modest fraction of leukotriene B₄ (LTB₄) and 5-hydroxyeicosatetraenoic acid (5-HETE) at doses reaching a maximum of 100 IU/ml. IFN of the and classes did not exert such effects. Addition of complement 5a to cells activated by IFN- caused induction of increased 5-li-poxygenase activity with unchanged release of AA. As only 16% of all CIBD patients had elevated IFN- levels as compared to 12% among the group of healthy volunteers, IFN- does not seem to be of importance for the perpetuation of the inflammatory reaction in ulcerative colitis or Crohn's disease, and other factors may therefore be responsible for activation of the inflammatory cells to production of LTB₄ and 5-HETE.