Frequency of anti-neutrophil cytoplasmic antibodies in patients with systemic lupus erythematosus / Frecuencia de los anticuerpos anticitoplasma de neutrófilo en pacientes con lupus eritematoso sistémico

ABSTRACT Introduction: Systemic 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. Methods: A 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. Results: Of 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). Conclusion: ANCAs 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.

RESUMEN Introducción: El lupus eritematoso sistémico (LES) es una enfermedad autoinmune sistémica. Los pacientes con LES muestran múltiples autoanticuerpos séricos, incluyendo los anticuerpos anticitoplasma de neutrófilo (ANCA, por sus siglas en inglés). Existen 2 técnicas principales para la detección de ANCA: inmunofluorescencia indirecta (IFI) y ensayo por inmunoadsorción ligado a enzimas (ELISA). En este estudio nuestro objetivo fue determinar la frecuencia y las asociaciones clínicas de los ANCA en pacientes con LES. Métodos: Realizamos un estudio transversal de 74 pacientes con LES en un hospital de alta complejidad de Colombia. La presencia de ANCA se evaluó por IFI, utilizando láminas con fijación de etanol, y con ELISA para determinar las especificidades para mieloperoxidasa (MPO)-ANCA y proteinasa 3 (PR3)-ANCA. Resultados: Fueron evaluados 74 pacientes con LES, 60 (81,1%) de ellos fueron positivos para ANCA. Por el contrario, solo un paciente mostró especificidad para PR3-ANCA por ELISA. La relación entre la positividad para ANCA por IFI y las características clínicas y serológicas fue estadísticamente significativa para compromiso renal (p = 0,0174) y para el índice de actividad de la enfermedad (Systemic Lupus Erythematosus Disease Activity Index [SLEDAI]) (p = 0,0308). Conclusiones: Los ANCA detectados mediante fijación con etanol por técnicas de IFI, son comunes en pacientes con LES. Sin embargo, la detección de especificidades para PR3 o MPO es rara; se destaca la importancia de la evaluación de estos autoanticuerpos mediante diferentes técnicas.

Clinical Characteristics and Outcomes of Patients With ANCA-Associated Vasculitides in a Colombian Hospital.

BACKGROUND/OBJECTIVE: Antineutrophil cytoplasmic antibody-associated vasculitides (AAVs) are uncommon systemic autoimmune diseases, of which few reports exist in Latin America. Our aim was to examine AAV evaluated in a high-complexity hospital in southwestern Colombia, with emphasis in severe forms. METHODS: A medical records review study of 67 patients was performed, and data were collected from electronic registries. Moderate and severe AAVs were defined as the presence of life-threatening complications, unfavorable Birmingham Vasculitis Activity Score outcomes, and hospitalization requirements at the time of diagnosis and by the last follow-up, between 2011 and 2019. Clinical manifestations, treatment, and outcomes were evaluated. The AAV subtypes were compared. RESULTS: A total of 67 cases were included. The majority were female (n = 44, 65.67%), and the median age was 52 (40-64) years. Granulomatosis with polyangiitis (GPA) was the most frequent with 42 patients (62.68%), followed by microscopic polyangiitis (MPA) and eosinophilic GPA, with 15 patients (22.38%) and 10 patients (14.92%), respectively. Forty-four patients (65.67%) presented pulmonary symptoms. The highest Birmingham Vasculitis Activity Score corresponded to MPA, with 21 (12-25) points. Fifteen patients (22.4%) were admitted to the intensive care unit throughout the course of the disease, of whom 10 had GPA. The longest stay and duration of mechanical ventilation were seen in MPA. The principal treatments were corticosteroids and cyclophosphamide, and the main outcome was end-stage renal disease. CONCLUSIONS: In this cohort of AAV, most of cases corresponded to GPA, and pulmonary manifestations were the most common. Microscopic polyangiitis was the more severe subtype as it showed worse impairment in clinical characteristics and intensive care unit requirements.