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Anti-myeloperoxidase antibodies: immunological characteristics and clinical associations
P Gueirard1, A Delpech, D Gilbert
1Laboratory of Immunology, Hôpital Charles Nicolle, Université de Rouen, France.
Abstract:
Antibodies directed against myeloperoxidase (anti-MPO) were detected, using a solid-phase ELISA and purified sputum myeloperoxidase as the substrate, in 54 sera from 22 patients. Anti-MPO were present in 17 patients with crescentic glomerulonephritis (CGN), Wegener's granulomatosis (WG) and microscopic polyarteritis (MPA), and thus are associated with different forms of vasculitis. Anti-MPO were also present in five out of 20 patients with systemic lupus erythematosus (SLE). Anti-MPO activity in SLE sera was low, in contrast to the high titers observed in patients with vasculitis. All positive sera had IgG anti-MPO (except two SLE sera) and most of them also contained low-titered IgM anti-MPO. Only three patients had high IgM anti-MPO activities, the significance of which remains to be determined. In patients with CGN, WG or MPA, the anti-MPO titer decreased following therapy and paralleled the disease activity. Thus, anti-MPO constitute a useful diagnostic tool and a sensitive marker of disease activity in this group of patients with vasculitis.
Insights
Antibodies against myeloperoxidase (anti-MPO) are linked to vasculitis, including crescentic glomerulonephritis, Wegener's granulomatosis, and microscopic polyarteritis. Anti-MPO levels effectively indicate disease activity and aid in diagnosis for these conditions.
Area of Science:
- Immunology
- Nephrology
- Rheumatology
Background:
- Myeloperoxidase (MPO) is an enzyme involved in inflammation.
- Autoantibodies against MPO (anti-MPO) are implicated in certain autoimmune diseases.
Purpose of the Study:
- To investigate the presence and significance of anti-MPO antibodies in patients with vasculitis and systemic lupus erythematosus (SLE).
- To evaluate anti-MPO as a diagnostic marker and indicator of disease activity.
Main Methods:
- Solid-phase ELISA using purified sputum MPO as substrate.
- Analysis of sera from patients with crescentic glomerulonephritis (CGN), Wegener's granulomatosis (WG), microscopic polyarteritis (MPA), and SLE.
Main Results:
- Anti-MPO antibodies were detected in 17/22 patients with CGN, WG, and MPA, indicating a strong association with vasculitis.
- Lower titers of anti-MPO were found in 5/20 patients with SLE.
- Anti-MPO IgG was prevalent, with some patients also having IgM anti-MPO.
- In vasculitis patients, anti-MPO titers decreased with therapy, correlating with disease activity.
Conclusions:
- Anti-MPO antibodies are valuable diagnostic markers for specific forms of vasculitis.
- Anti-MPO titers serve as sensitive indicators of disease activity in CGN, WG, and MPA.
- The role of high IgM anti-MPO requires further investigation.