Relationship between anti-neutrophil cytoplasmic antibody determined with conventional binding and the capture assay, and long-term clinical course in vasculitis.
OBJECTIVE
To evaluate the relationship between anti-neutrophil cytoplasmic antibody (ANCA) measured with two different methods and long-term clinical course in vasculitis.


METHODS
Retrospective determination of ANCA with two different assays for detection of PR3-ANCA, conventional direct binding ELISA and capture ELISA using monoclonal antibodies against PR3. The 245 ANCA determinations were performed from frozen blood samples collected three to four times a year in each patient.


METHODS
Department of Nephrology at a Swedish University Hospital.


METHODS
A total of 10 ANCA-positive patients with vasculitis caused by Wegener's granulomatosis (WG) or microscopic polyarteritis (MPA) and a very long follow-up time (mean 9 years, range 5-15.5 years).


RESULTS
The total number of episodes with active vasculitis was 29 and all of them (100%) were detected by the capture technique whilst the conventional technique detected 23 (79%). The mean number of episodes with active disease requiring treatment with steroids and cytotoxic drugs was three per patient (range 1-6). At the time of clinical relapse of the vasculitis disease, the ANCA titre using the capture technique was either increasing or showed a very high value in all cases. The pattern of capture ANCA response could be subdivided into three categories: a close (four patients), an intermediate (three patients), and no (three patients) relationship between capture ANCA level and long-term clinical course.


CONCLUSIONS
Detection of PR3-ANCA by the capture ELISA showed a higher sensitivity than that obtained by the direct ELISA in diagnosing relapse during follow-up of patients with vasculitis. The specificity of the capture ANCA was, however, low, as high levels occurred in patients without clinical disease activity.
Gisslén
K
K
Department of Nephrology, Sahlgrenska University Hospital, Göteborg, Sweden.
Wieslander
J
J
Westberg
G
G
Herlitz
H
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D001167:Arteritis / Q000175:diagnosis / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D014890:Granulomatosis with Polyangiitis / Q000175:diagnosis / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D053146:Myeloblastin; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012697:Serine Endopeptidases / Q000276:immunology; D014657:Vasculitis / Q000175:diagnosis / Q000276:immunology*
D019268:Antibodies, Antineutrophil Cytoplasmic; D012697:Serine Endopeptidases; D053146:Myeloblastin