Finkielman JD et al. (2007) ANCA are detectable in nearly all patients with active severe Wegener's granulomatosis. Am J Med 120: 643.e9–e14

The role of antineutrophilic cytoplasmic antibody (ANCA) in the pathogenicity of Wegener's granulomatosis is controversial, and the variability in results obtained from different serum ANCA assays is considerable. Finkielman and colleagues used several assays to determine the frequency of ANCA presence in a cohort of patients with Wegener's granulomatosis, and examined whether disease severity affects the results of these assays.

Serum samples were obtained from 180 patients (mean age 47 years, 60% men, 92% white, median time since symptom onset 17 months) who were enrolled in the Wegener's Granulomatosis Etanercept Trial. Of these, 128 (71%) had severe disease (defined as life-threatening or vital-organ-threatening) and 52 (29%) had limited disease. Baseline serum samples were assayed for several ANCA subtypes using standard indirect immunofluorescence, direct ELISA, and two capture ELISA assays.

Immunofluorescence detected ANCA in 160 (89%) patients (cytoplasmic ANCA staining [c-ANCA] in 136 patients, perinuclear ANCA staining [p-ANCA] in 24 patients). Direct ELISA detected proteinase 3 (PR3)-ANCA in 133 (74%) patients; this ANCA subtype was detected in 136 (76%) patients and 148 (82%) patients using the mature-PR3 capture ELISA and anti-c-myc capture ELISA, respectively. Overall, 166 (92%) patients had detectable ANCA. Patients with severe disease were more likely to be ANCA-positive than those with limited disease (96% vs 83%).

The authors conclude that ANCA is detectable in almost all patients with Wegener's granulomatosis, and that use of the full range of assays is required to characterize the presence of all PR3-ANCA accurately and reliably.