Frequency of anti-neutrophil cytoplasmic antibodies in patients with systemic lupus erythematosus

Abstract

IntroductionSystemic lupus erythematosus (SLE) is a multisystem autoimmune disease. Patients with SLE exhibit multiple serum autoantibodies, including anti-neutrophil cytoplasmic antibodies (ANCAs). There are two main techniques to detect ANCAs: indirect immunofluorescence (IIF) and enzyme-linked immunosorbent assay (ELISA). In this study, an attempt was made to determine the frequency and clinical associations of ANCAs in patients with SLE. MethodsA cross-sectional study was conducted in a tertiary care hospital in Colombia that included 74 patients with SLE. The presence of ANCAs was assessed using IIF with ethanol-fixed slides, and ELISA was used to detect antibody specificities for myeloperoxidase (MPO)-ANCA and proteinase 3 (PR3)-ANCA. ResultsOf the 74 patients with SLE evaluated, 60 (81.1%) of them were ANCA-positive by IIF. By contrast, only one patient showed specificity for PR3-ANCA by ELISA. The relevance of ANCA positivity by IIF and clinical and serological features was significant for renal involvement (p=.0174), and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) (p=.0308). ConclusionANCAs are common in the serum of patients with SLE, as detected by ethanol-fixed slides with IIF staining. However, detection of specificity to PR3 and/or MPO is rare, thus highlighting the importance of detecting these autoantibodies by different techniques.