IgA- and SIgA anti-PR3 antibodies in serum versus organ involvement and disease activity in PR3-ANCA associated vasculitis.

• Circulating IgA class anti-neutrophil cytoplasm antibodies (ANCA) directed against proteinase 3 (PR3) have been reported in ANCA-associated vasculitis (AAV) with mucosal involvement. However, secretory IgA (SIgA) PR3-ANCA has not been reported previously. In this study we compared serum levels of SIgA PR3-ANCA and IgA PR3-ANCA with IgG PR3-ANCA in relation to disease characteristics. Among 73 patients with AAV and PR3-ANCA at diagnosis, 84% tested positive for IgG PR3-ANCA, 47% for IgA-ANCA and 36% for SIgA PR3-ANCA at the time of sampling for the present study. IgA and IgG PR3-ANCA were similarly represented among patients with different organ manifestations, i.e. upper airway, lung or kidney at time of sampling. However, SIgA PR3-ANCA was significantly less represented among patients with upper airway involvement. During active disease, the proportions of IgA PR3-ANCA and SIgA PR3-ANCA positive patients were significantly higher as compared to inactive disease. Eight patients were prospectively sampled during 24 months from onset of active disease. In these patients, IgA PR3-ANCA and SIgA PR3-ANCA more often turned negative after remission induction as compared to IgG PR3-ANCA. Our findings suggest that serum IgA PR3-ANCA and SIgA PR3-ANCA are more closely related to disease activity in AAV as compared to IgG PR3-ANCA. Further studies are required to reveal if this has implications for disease activity monitoring. The mean number of PR3-ANCA isotypes increased along with disease activity, suggesting a global B-cell activation during active disease. This article is protected by copyright. All rights reserved.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Dermatologi och venereologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Dermatology and Venereal Diseases (hsv//eng)

Keyword

ANCA-associated vasculitis; IgA PR3-ANCA; Mucosal immunity; disease activity

Publication and Content Type

ref (subject category)

art (subject category)