Anticuerpos Anti-C1q como marcadores de compromiso renal en pacientes con lupus eritematoso sistémico / Anti-C1q antibodies as markers of renal compromise in patients with systemic lupus erythematosus

Resumen El compromiso renal en el lupus eritematoso sistémico (LES) es uno de los mayores determinantes del curso y pronóstico de estos pacientes. Existe evidencia de la asociación de anticuerpos anti-C1q y el desarrollo de nefritis lúpica. El objetivo de este estudio fue determinar la prevalencia de anticuerpos anti-C1q y su asociación con nefritis lúpica en pacientes colombianos con LES. Métodos: Estudio de corte transversal en el cual se incluyeron 80 pacientes con diagnóstico de LES según criterios del Colegio Americano de Reumatología. La cuantificación de anticuerpos anti-C1q séricos se realizó por ELISA, se consideraron positivas concentraciones ≥15 U/ml. Resultados: Los pacientes eran predominantemente mujeres (87%) y 43,7% tuvieron proteinuria >0,5 g/día, la cual fue más común en pacientes jóvenes y apareció tempranamente en la enfermedad. Cuarenta y cuatro (55%) de los pacientes tenían anticuerpos anti-C1q positivos, en quienes la proteinuria fue más frecuente (OR=4.3, IC95% 1.7 - 11, p=0.003). Se encontró correlación inversa débil entre los títulos de anti-C1q, el consumo de C3 (r=-0.54, p<0.001) y la depuración de creatinina (r=-0.33, p=0.035); una correlación directa débil, con la proteinuria (r=0.35, p=0.024) y la actividad de la enfermedad, la cual se determinó con el Índice de Actividad de Enfermedad (SLEDAI) (r=0.48, p<0.0001). Conclusiones: Los anticuerpos anti-C1q pueden ser útiles en la evaluación de la nefritis lúpica activa, y podrían ser implementados como un marcador diagnóstico de nefritis lúpica y como un posible marcador de actividad de la enfermedad en pacientes con LES, tal como lo ha sugerido la Liga Europea contra el Reumatismo (EULAR).

Summary Renal involvement in systemic lupus erythematosus (SLE) is one of the major determinants Anti-C1q antibodies of the course and prognosis of these patients. There is evidence of the association of Anti-DNA antibodies anti-C1q antibodies and the development of lupus nephritis. The aim of this study was to determine the prevalence of anti-C1q antibodies and its association with lupus nephritis in Colombian patients with SLE. Methods: 80 SLE patients as defined by the American College of Rheumatology criteria. Quantification of anti-C1q antibodies in patients' sera was performed by ELISA and concentrations greater than 15U/ml were considered positive. Results: Patients were predominantly women (87%) and 43.7% of them had proteinuria > 0.5 g / 24 hours which was more common in younger patients and early in the course of the disease. Forty-four (55%) of patients had positive anti-C1q, in whom, proteinuria was more frequent (OR = 4.3 95% CI 1.7 - 11, p = 0.003). A weak inverse correlation between anti-C1q titers, C3 consumption (r = -0.54, p <0.001) and creatinine clearance was found (r = -0.33, p = 0.035); similarly, we also found a weak direct correlation with proteinuria (r = 0.35, p = 0.024) and disease activity ascertained with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) (r = 0.48, p <0.0001). Conclusions: Anti-C1q antibodies might be valuable for the evaluation of active lupus nephritis, and might be valuable for the evaluation of active lupus nephritis, and could be included as a diagnostic marker of lupus nephritis and maybe as a marker for disease activity, as suggested by the European League Against Rheumatism (EULAR).

A New Digital Image Processing Technique for Mixed Pattern Analysis of Anti-neutrophil Cytoplasmic Antibody Test / 대한류마티스학회지

OBJECTIVE: Anti-neutrophil cytoplasmic antibody (ANCA) is an important marker for the diagnosis and the classification of rheumatic diseases and systemic vasculitis. If the autoantibodies that can be stained in the nucleus of neutrophil used for substrate of ANCA test, there's a need for its differential diagnosis from real p-ANCA. This paper focuses on digital image processing technique for the differentiation of p-ANCA without performing additional tests. METHODS: Positive ANCA results which showed mixed fluorescent pattern were transformed into digital image. Using Matlab (MathWorks, U.S.A.), we developed 2D to 3D transformation method and virtual tomography for the interpretation of mixed fluorescent pattern, and compared these results with ANA and anti-DNA test by indirect immunofluorescence (IIF) method using IT-AIT, IT-ANCA, and IT-DNA kit (ImmunoThink, Korea). RESULTS: By applying the 3D transformation method and virtual tomography to the results of ANCA test where combined antibodies exist, we were able to separate each different fluorescent pattern that were difficult to separate by manual reading. CONCLUSION: The new digital image analysis methods developed in this study displace some of the disadvantages of IIF method. Therefore, these methods can easily be applied to complex samples, and can allow rapid and accurate tests for rheumatic diseases and other autoimmune diseases.