Use of Antineutrophil Cytoplasmic Autoantibodies in Diagnosing Vasculitis in a Chinese Patient Population

Abstract

Antineutrophil cytoplasmic autoantibodies (ANCA) have been used as markers of systemic vasculitides, including microscopic polyarteritis (MPA) and Wegener’s granulomatosis. The diagnostic potential of ANCA assays together with antibodies against the neutrophil enzymes myeloperoxidase (MPO) and proteinase 3 for detecting a systemic vasculitis was tested in a Chinese patient population. 672 sera were received for ANCA assay, and ANCA detected by indirect immunofluorescence was positive in 73 sera from 42 patients. Of the 42 patients, 3 had cytoplasmic ANCA, while 39 had a perinuclear pattern. There was no patient with Wegener’s granulomatosis. Two cytoplasmic ANCA positive patients suffered from ulcerative colitis. Another cytoplasmic ANCA positive patient was a carrier of human immunodeficiency virus. Of the 39 perinuclear ANCA positive patients, 10 had MPA. Eight of them were tested for anti-MPO antibody, and all were positive. Other immune disorders that were perinuclear ANCA positive included: 13 patients with systemic lupus erythematosus, 3 with mixed connective tissue disease, 1 with Goodpasture’s syndrome, 2 with inflammatory bowel disease, and 2 patients with IgA nephropathy. Anti-MPO antibody was not specific for MPA, and 7 out of the 13 patients with systemic lupus erythematosus were anti-MPO antibody positive. Our study suggests that ANCA and anti-MPO antibody are not specific for MPA in a Chinese population. They would alert the clinician of the possibility of vasculitis, but a clinicopathological correlation is essential in making the diagnosis.

Detection Rate and Antigenic Specificities of Antineutrophil Cytoplasmic Antibodies in Chinese Patients with Clinically Suspected Vasculitis

“…The second concerned antigenic predominance. MPO and PR3 are the two major ANCA antigens for Chinese patients with AASV; however, the prevalence of P-ANCA/MPO-ANCA was much higher than that of C-ANCA/PR3-ANCA, with a ratio of 7:1, a finding that agreed with reports from Hong Kong (5,6). Limited observations suggest that the ANCA-associated disease process in northern latitudes more often produces the phenotype of Wegener's granulomatosis, while the phenotypic expression in warmer climates is more often that of microscopic polyangiitis and idiopathic pauci-immune necrotizing glomerulonephritis (14).…”

Epidemiology of systemic vasculitis

“…Some previous studies of white populations have noted a predominance of males while the Chinese study reported an equal number of males and females of all ages, predominance of females in those 20 years of age and under (females:males; ratio 4:1). Similar findings have been reported from Hong Kong (MPO:PR3; 7:1) [17,18].…”

Sulfasalazine Pulmonary Toxicity in Ulcerative Colitis Mimicking Clinical Features of Wegener's Granulomatosis

“…Although a positive perinuclear accentuated ANCA (p-ANCA) is common in inflammatory bowel disease, a positive c-ANCA is not. [5][6][7][8] We now describe a patient with ulcerative colitis (UC) who presented with noninfectious peripheral pulmonary infiltrates, a persistently elevated c-ANCA, and pulmonary symptoms mimicking WG who was later diagnosed as hav¬ ing sulfasalazine pulmonary toxicity.…”