Antineutrophil Cytoplasmic Antibodies in Inflammatory Bowel Disease and Collagenous Colitis: No Association with Lactoferrin, β-Glucuronidase, Myeloperoxidase, or Proteinase 3.

: Perinuclear antineutrophil cytoplasmic antibodies (P-ANCA) occur frequently in ulcerative colitis (UC) but not in Crohn's disease (CD). Their pathogenetic importance is unknown, and studies of associated antigens have been inconsistent. Indirect immunofluorescence technique was used to screen the occurrence of antineutrophil cytoplasmic antibodies in 36 patients with UC, in 37 patients with CD, in 38 patients with collagenous colitis (CC), and in 190 controls. Enzyme immunoassays (EIAs) were used to detect the target antigen(s) by using lactoferrin (Lf), β-glucuronidase (β-Glc), myeloperoxidase (MPO), and proteinase 3 (PR3) as the substrates. P-ANCA was found in 23 (63.9%) of 36 of the patients with UC, in two (5.4%) of 37 with CD, in four (10.5%) of 38 with CC, and in four (2.1%) of 190 of healthy controls. No case of cytoplasmic staining pattern (C-ANCA) was found. With EIA, P-ANCA in IBD or CC was not found to be associated with reactivity to Lf, β-Glc, MPO, or PR3, which confirms findings reported by others. P-ANCA was found in a higher frequency in UC than in CD or CC. The antigens of P-ANCA remain unidentified.