Welcome to the Autoimmunity 2021 Congress Calendar

Background and Aims

Applying for ISO 15189 accreditation remains a real challenge for specialized laboratories. In the field of autoimmunity, beside the crucial problem linked to the absence of standardization, laboratories have to manage the analytical performances of the large panel of assays available in the market. The evaluation of such performances involves not only the clinical relevance of the assays but also their measurement precision for which no reference values are available on biorepositories.

Methods

On an initiative of the French EASI (European Autoimmunity Standardization Initiative) group, French diagnostic biomedical laboratories were proposed to participate to a survey aiming to analyze the coefficients of variation (CVs) of intra-run and inter-run variability obtained with assays quantifying 14 different autoantibodies. Two performance goals corresponding to the 90^th percentile and the 50^th percentile defined for three levels of concentration were calculated. The impact on the assay performances of the number of measurements, the nature of the internal quality control (IQC) and the method, were also analyzed.

Results

436 and 651 values of intra-run and inter-run CVs, respectively, were collected. The 50^th percentile performance goals were comprised between 2.9% and 10.7% for the intra-run CVs, and between 2.8% and 13.2% for the inter-run CVs. CVs calculated from 10 values were similar to those obtained from more values. Higher imprecision was observed when the antibody levels of the IQC was lower than 2 fold the positive threshold.

Conclusions

Our results allow proposing some acceptability limits for the performances of the autoimmunity assays, compatible with real life in diagnostic laboratories.

Background and Aims

Automated systems for anti-nuclear antibody (ANA) detection by indirect immunofluorescence analysis (IFA) provide an estimate of the fluorescence intensity (FI). The aim was to evaluate whether variability in FI estimations could be reduced by using a standard preparation.

Methods

Two standards [IUIS/ASC ANA#4 (large speckled; 1/8 dilution) and DFS Megapool] and three serum samples were distributed to 34 laboratories using automated IFA (ZenitPro;n=2, Zenit G-sight;n=5, EUROPattern;n=10, NOVAView;n=14, Image Navigator;n=3). Samples were analysed in duplicate in 5 runs. Sample1 was also distributed by the Belgian External Quality Assessment scheme (EQA). Instrument-specific FI and/or estimated titers were documented. Besides, relative fluorescence or light units (RLU) and titer ratios were calculated based on the two standards.

Results

EQA results revealed an inter-laboratory FI variability that tended to be lower for automated compared to manual IFA analysis.

With almost every automated IFA system, outlier results were observed.

Imprecision results revealed pattern-dependent coefficient of variations (CV%), with lowest CV% for DFS Megapool for all substrates.

The use of the DFS Megapool as a reference material to calculate RLUs and titer ratios reduced inter-laboratory variation (e.g. sample1: CV% without standard: 12.1-16.9% versus CV% with standard: 1.4-8.9%;p<0.05) and aligned results between instruments from the same manufacturer and between instruments from different manufacturers. Such effect was not observed when the IUIS/ASC ANA#4 was used as reference material.

Conclusions

Automated IFA analysis allows to align FI measurements, if a common protocol is applied, a total process iQC program is implemented and a suitable standard is available. The DFS Megapool presented the best reproducibility.

Background and Aims

Background and aims: Infliximab (IFX) is a monoclonal therapeutic anti-TNF antibody with proven efficiency in chronic inflammatory diseases. However, a significant number of patients have no primary response or lose response becoming secondary non-responders. The production of anti-drug antibodies (ADAb) increasing IFX serum clearance has been identified as a possible explanation. However the prevalence and kinetics of ADAb are not well described. Our aim was to evaluate the occurrence of ADAb in a large cohort of infliximab-treated patients.

Methods

Method: A cohort of 817 serum samples sent to our lab between 2016 and 2019 for concomitant evaluation of infliximabemia and ADAb (Lisa-Tracker, Théradiag, France) was retrospectively studied.

Results

Results: In our cohort, 91 out of 817 samples (11.13 %) were found positive for ADAb. Among them, 53 samples (58.2 %) displayed a concentration of ADAb superior to 200 µg/ml. The 91 positive samples corresponded to 71 patients and we had a longitudinal follow-up for 14 patients. Among these later, 11 patients had a stable level of ADAb during several months (>200 µg/ml for 9 patients) while we observed a modulation of ADAb levels in the 3 other ones (down-modulation in 2 cases and up-modulation in one case).

Conclusions

Conclusions: We showed here that the prevalence of ADAb during infliximab therapy is quite elevated (11, 13 %). Moreover, in our study, the ADAb levels are mainly high and seem stable. However in a minority of patients we could observe a modulation of ADAb levels during the infliximab therapy.

Background and Aims

Systemic Lupus Erythematosus (SLE) is a chronic multisystemic autoimmune inflammatory disease that may cause lymphadenopathies. The present study aimed to report the etiology of lymphadenopathies and the possible role of long-standing rituximab treatment on the expression of B cell-stimulating factors in lymph nodes.

Methods

This a retrospective cohort of 205 patients with SLE, of which 13 patients (6.3%) had lymphadenopathy. Immunohistochemistry was performed in 4 available cases of follicular hyperplasia to compare the expression of BAFF, BAFFR, and BCMA between patients who received Rituximab and those who did not.

Results

The etiology of 13 lymph nodes was as follows: follicular hyperplasia in 7 (53.85%) patients, Kikuchi's syndrome in 3 (23.08%), metastasis of papillary necrotizing lymphadenitis in 1 (7.69%), follicular B-cell lymphoma in 1 (7.69%) and tuberculosis in 1 (7.69%). Three patients presenting lymphadenopathies were in remission for several years and were receiving monotherapy with rituximab. Immunohistochemical study in one of these patients showed BAFF overexpression in the follicles and moderate expression of BAFF-R confined to the mantle zone (Figure 1). No significant differences were seen on the expression of BAFF, BAFF-R and BCMA when comparing with patients who did not received Rituximab.

Conclusions

The most common cause of lymphadenopathies in our series was follicular hyperplasia. Immunohistochemistry of one patient who received Rituximab showed overexpression of BAFF and moderate expression of BAFF-R. This finding could suggest that lymph node enlargement after CD20 depletion therapy may be mediated by compensatory expression of BAFF and its receptors.

Background and Aims

Autoimmunity is a complex science in continuous expansion, as knowledge grows and more antibodies test are available more difficult becomes stay update. It is not uncommon to see physicians ordering an extensive set of autoantibodies test to “screen for autoimmunity”, showing up sometimes unexpected results that far from clear the diagnosis creates confusion and unnecessary worries to patients. To ameliorate the problem, we propose a digital interactive autoimmune guide that makes handly, agile and reliable the consult of the necessary knowledge in autoimmunity.

Methods

-Development of an interactive digital autoimmune guide in format web and app that offers the possibility to make quick consults searching by three categories (autoantibodies, diseases, signs and symptoms), and where each item is linked with its related content.

-A collaborative platform like Wikipedia but professional only accredited professionals would be able to edit and add content.

Results

Unfinished version here: www.immunoreference.com

Conclusions

-Autoimmunity knowledge is in continuous expansion, it is necessary a platform to canalize that growing in a systematized and effective way.

-A collaborative approach peer to peer may be an effective way to keep the platform updated.

-This platform may contribute to guiding clinical decisions, optimize autoantibodies test and help to interpret correctly its results.