21.   The pathophysiological importance of the ulcerative colitis associated perinuclear antineutrophil cytoplasmic antibodies is still poorly understood.

22.   The presence of perinuclear antineutrophil cytoplasmic antibodies in unaffected family members of ulcerative colitis patients favours this view.

23.   Of particular interest is the observation that primary sclerosing cholangitis patients are also perinuclear antineutrophil cytoplasmic antibody positive.

24.   Possibly, ulcerative colitis and primary sclerosing cholangitis associated neutrophil cytoplasmic antibodies recognise the same antigen.

25.   In conclusion, our study confirms that perinuclear antineutrophil cytoplasmic antibodies are indeed demonstrable in the large majority of ulcerative colitis patients.