Аннтотация

To the editor, In the excellent study recently published in the Annals of the Rheumatic Disease, Damoiseaux et al showed a high diagnostic performance of antigen-specific immunoassay for the detection of myeloperoxidase (MPO) and proteinase 3 (PR3) antineutrophil cytoplasmic antibodies (ANCAs). These data challenge the role of indirect immunofluorescence in the ANCA testing algorithm. In our centre, we have discarded ANCA indirect immunofluorescence more than a decade ago. Therefore, new data showing the feasibility of screening by antigen-specific immunoassay have a particular value for us. In the recent series of 284 patients with ANCA-associated vasculitides, we have detected ANCAs by this approach in 96.9% of patients with microscopic polyangiitis (MPA) but only in 72.7% of patients with granulomatosis with polyangiitis (GPA) (table 1). The latter result can be explained by a relatively high occurrence of localised GPA in our series, since a rate of ANCA positivity reached 92.2% in patients with renal GPA. ANCA testing should be performed only in the clinical context since PR3-ANCA and MPO-ANCA can be found in the other conditions than vasculitis, for example, infective endocarditis, tuberculosis, primary sclerosing cholangitis and interstitial lung diseases. The results of several studies suggest that in such patients, ANCAs have not been merely a chance finding and may be clinically relevant, for example, a high prevalence of ANCAs was identified in unselected patients with infective endocarditis (24%). Seropositive patients presented more commonly with a subacute form of infective endocarditis leading to multiple valve involvement and a more frequent renal impairment.