The nitroblue tetrazolium test in Crohn's disease and ulcerative colitis.

In subjects with Crohn's disease and ulcerative colitis, an increased percentage of peripheral blood neutrophils reduces the dye nitroblue tetrazolium. This is probably a non-specific index of inflammatory activity. There is no evidence that defective neutrophil function, as measured by this test, contributes to granuloma formation in Crohn's disease.