Diagnostic accuracy of serum calprotectin measured by CLIA and EIA in juvenile idiopathic arthritis: a proof-of-concept study.

Objective: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are used to assess disease activity in juvenile idiopathic arthritis (JIA). However, because these biomarkers do not always differentiate between active and inactive disease, there is a need for alternative markers such as serum calprotectin (sCal). The main aim of this proof-of-concept study was to assess the diagnostic accuracy of sCal in patients with JIA. Secondary aims were to identify the optimal sCal cut-off levels to define active disease and evaluate the association between these biomarkers and disease activity status. Methods: Serum samples were obtained from 25 pediatric patients with JIA. Serum calprotectin levels were determined by two different assays, the QUANTA FLASH chemiluminescence immunoassay (CLIA) from Inova Diagnostics and the solid-phase enzyme immunoassay (EIA) from Bühlmann Laboratories. Diagnostic accuracy was assessed for sCal CLIA, sCal EIA, CRP, and ESR. The results obtained by the CLIA and EIA methodologies were compared. We also evaluated the association between the individual each biomarkers (sCal CLIA, sCal EIA, CRP, and ESR) and disease activity (according to JADAS-27 criteria and the ACR criteria modified by Anink and colleagues). Results: For both sCal assays (CLIA and EIA), the optimal cut-off level (ROC analysis) was the same (2.3 µg/ml). Serum calprotectin levels measured by CLIA and EIA were strongly correlated with each other (Kendall's tau-b, 0.71; p < 0.001). Compared to ESR and CRP, sCal CLIA and EIA were both more accurate (i.e., greater sensitivity) in identifying patients with active disease. By contrast, ESR and CRP were more effective in identifying patients in remission (i.e., better specificity). Conclusion: This proof-of-concept study shows that determination of serum calprotectin levels with CLIA or EIA can accurately identify the presence of active disease in patients with JIA.

Inter-laboratory comparison of routine autoantibody detection methods for autoimmune neuropathies and myasthenia gravis.

Serological tests are important to detect autoantibodies (autoAbs) in patients with autoimmune neuropathies (AN) and myasthenia gravis (MG) as they are biomarkers for diagnosis, stratification, treatment selection, and monitoring. However, tests to detect autoAbs frequently lack proper standardization and results differ across diagnostic laboratories. We compared results for tests routinely performed in Spanish diagnostic laboratories to detect AN and MG autoAbs. In the Spanish Society of Immunology Autoimmunity Group national workshop, serum samples from 13 patients with AN or MG were tested for anti-ganglioside, anti-myelin-associated glycoprotein (MAG), anti-nicotinic acetylcholine receptor (AChR), and anti-muscle-specific kinase (MuSK) autoAbs using reference methods and were distributed for analysis to 27 participating laboratories using their routine methods. Overserved were inter-laboratory variability and worryingly low sensitivity, especially for anti-ganglioside immunoglobulin G and anti-MAG autoAb detection. This pilot study reflects autoAbs detection state of the art in AN and MG testing in leading diagnostic laboratories in Spain, highlighting the need for standardization prior to clinical use.

Prognostic significance of lymphocytic foci composition in minor salivary gland biopsies for severe disease flare and severity in Sjögren's syndrome: a 3-year follow-up cohort study.

Introduction: This was an ambispective cohort study evaluating the prognostic significance of lymphocytic foci and its lymphoid composition in minor salivary gland biopsy (MSGB) for short-term disease flare and severity in Sjögren's syndrome (SS). Methods: The inclusion criteria comprised individuals meeting the ACR/EULAR 2016 criteria who underwent MSGB with an infiltration of more than 50 lymphocytes and received clinical diagnosis between September 2017 and December 2018. Patients with inadequate biopsy samples were excluded. The number of lymphocytic foci and their lymphoid composition in MSGB were assessed using immunofluorescence staining. Major organ damage and improvements in the EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI) were measured. Statistical analyses, including Cox and linear regressions, were conducted. Results: A total of 78 patients with at least one lymphocytic focus were included in the study. The presence of higher T-cell counts in lymphocytic foci in MSGB was associated with severe disease flare, and a logarithmic transformation of T-cell count indicated increased risk (HR 1.96, 95% CI 0.91-4.21). Improvements in the ESSDAI were associated with higher total lymphocyte count and T- and B-cell numbers in the lymphoid composition of the lymphocytic foci. Seropositive patients exhibited higher T CD4+ cell numbers. Correlation analysis showed negative associations between age and lymphocytic foci and the T-cell count. Positive correlations were observed between antinuclear antibody (ANA) titers and total lymphocyte numbers. Discussion: Patients with a higher number of T cells in the lymphocytic infiltrates of lymphocytic foci may have a two-fold risk of severe disease flare. The number of B cells and T CD4+ cells in the lymphocytic infiltrates of lymphocytic foci showed a weak but positive relation with the ESSDAI improvement during follow-up. Age and seropositivity appeared to influence the lymphoid composition of the lymphocytic foci.

Miastenia gravis / No disponible

No disponible

Autoanticuerpos en enfermedades autoinmunes / No disponible

No disponible

Miastenia gravis «seronegativa» y anticuerpos antiMuSK positivos: descripción de una serie española / «Seronegative» myasthenia gravis and antiMuSK positive antibodies: description of Spanish series

Fundamento y objetivo: Recientemente se ha descrito que un subgrupo de pacientes con miastenia gravis generalizada seronegativa tienen anticuerpos frente a la molécula tirosincinasa muscular específica (AcMuSK). Nuestro objetivo es describir nuestra serie de pacientes con miastenia generalizada y AcMuSK positivo. Pacientes y método: Mediante radioinmunoanálisis se determinaron los anticuerpos en el suero de 26 pacientes con miastenia generalizada seronegativa. Se identificaron 9 pacientes con AcMuSK, cuyos datos clínicos y terapéuticos se revisaron. Resultados: De los 9 pacientes, 8 eran mujeres de entre 20 y 40 años. Todos presentaron debilidad bulbar grave, bien inicialmente o durante la evolución. El 77% presentó también clínica ocular y un 44%, fatigabilidad leve en las extremidades. Ninguno mejoró tras la timectomía. La respuesta a anticolinesterásicos fue variable. Todos respondieron a inmunoterapia, aunque un 30% precisó politerapia. Conclusiones: Los AcMuSK distinguen a un subgrupo de pacientes, el 34,61% en esta serie, con miastenia generalizada seronegativa que presentan una clínica homogénea con debilidad de predominio bulbar. Conocer los mecanismos inmunopatológicos de los AcMuSK permitirá entender la variabilidad de respuesta a los anticolinesterásicos, así como la falta de respuesta a la timectomía, en estos pacientes

Background and objective: Recently, the presence of antibodies to a muscle-specific tyrosine kinase (MuSK) has been reported in some patients with seronegative generalized myasthenia gravis. Our objective was to describe a group of patients who were positive for anti-MuSK antibodies. Patients and method: Detection of antibodies using a radioimmunoassay was performed in the serum of 26 patients with generalized myasthenia gravis. We identified 9 patients with anti-MuSK antibodies (MuSK+). Clinical and therapeutic data from these patients were reviewed. Results: Eight of nine patients were women aged between 20 and 40 years. Clinically, all of them showed prevalent bulbar signs, initially or during the progression of the disease. 77% of patients showed ocular involvement and 44% had symptoms of fatigability involving limbs. None of them improved upon thymectomy. Response to acetylcholinesterase inhibitors was variable. All of them responded to immunotherapy, although 30% required polytherapy. Conclusions: The study of anti-MuSK antibodies defines a subgroup of patients, 34,61% in our series, with seronegative generalized myasthenia. This group is characterized by an homogenous clinical presentation with prevalent bulbar symptoms. The knowledge of the immunopathogenic mechanisms of anti-MuSK antibodies will allow a better understanding of both the variable response to acetylcholinesterase inhibitors and the absence of response to thymectomy in these patients