New automated indirect immunofluorescent antinuclear antibody testing compares well with established manual immunofluorescent screening and titration for antinuclear antibody on HEp-2 cells

A novel way to evaluate autoantibody interference in samples with mixed antinuclear antibody patterns in the HEp-2 cell based indirect immunofluorescence assay and comparison of conventional microscopic and computer-aided pattern recognition

BACKGROUND

A major challenge of the HEp-2 cell-based indirect immunofluorescence (IIF) assays is the correct identification of the individual anti-nuclear antibodies (ANAs) if more than one is present in a sample. We created artificial mixes by pooling two different samples with a single autoantibody in different titers. Comparison of the expected and observed patterns and titers clarifies the interference between the two tested ANAs.

METHODS

Serum samples with a single homogeneous or speckled ANA pattern were serially diluted and mixed in 16 combinations, providing end-point titers of 1:5,120 to 1:80 for both patterns. These mixes were tested by a HEp-2 IIF assay and were evaluated by conventional evaluation, the EUROPattern (EPa) system and on-screen analysis.

RESULTS

Homogeneous pattern can alter the identification of the speckled pattern much more than vice versa, but both has an interfering effect on the other. The effect of the interfering on the tested pattern was higher if the titer of the former one was higher. The pattern recognition efficacy of conventional and the on-screen evaluation was similar and superior compared to the EPa analysis.

CONCLUSIONS

The application of artificial mixed samples can help the evaluation of the efficacy of manual and computer-aided ANA HEp-2 pattern recognition.

Evaluation of a Fully Automated Antinuclear Antibody Indirect Immunofluorescence Assay in Routine Use

Indirect immunofluorescence assay (IFA) using HEp-2 cells as a substrate is the gold standard for detecting antinuclear antibodies (ANA) in patient serum. However, the ANA IFA has labor-intensive nature of the procedure and lacks adequate standardization. To overcome these drawbacks, the automation has been developed and implemented to the clinical laboratory. The purposes of this study were to evaluate the analytical performance of a fully automated Helios ANA IFA analyzer in a real-life laboratory setting, and to compare the time and the cost of ANA IFA testing before and after adopting the Helios system. A total of 3,276 consecutive serum samples were analyzed for ANA using the Helios system from May to August 2019. The positive/negative results, staining patterns, and endpoint titers were compared between Helios and visual readings. Furthermore, the turnaround time and the number of wells used were compared before and after the introduction of Helios system. Of the 3,276 samples tested, 748 were positive and 2,528 were negative based on visual readings. Using visual reading as the reference standard, the overall relative sensitivity, relative specificity, and concordance of Helios reading were 73.3, 99.4, and 93.4% (κ = 0.80), respectively. For pattern recognition, the overall agreement was 70.1% (298/425) for single patterns, and 72.4% (89/123) for mixed patterns. For titration, there was an agreement of 75.9% (211/278) between automated and classical endpoint titers by regarding within ± one titer difference as acceptable. Helios significantly shortened the median turnaround time from 100.6 to 55.7 h (P < 0.0001). Furthermore, routine use of the system reduced the average number of wells used per test from 4 to 1.5. Helios shows good agreement in distinguishing between positive and negative results. However, it still has limitations in positive/negative discrimination, pattern recognition, and endpoint titer prediction, requiring additional validation of results by human observers. Helios provides significant advantages in routine laboratory ANA IFA work in terms of labor, time, and cost savings. We hope that upgrading and developing softwares with more reliable capabilities will allow automated ANA IFA analyzers to be fully integrated into the routine operations of the clinical laboratory.

A multi-centre study for standardization of antinuclear antibody indirect immunofluorescence screening with automated system

INTRODUCTION

ndirect immunofluorescence assay (IFA) using HEp-2 as substrate plays a consolidate role for the detection and measurement of ANA, which is currently considered as the reference method for detection. Manual operation is still very common in China, therefore, the need of standardization and automation for ANA-IFA detecting has been highlighted.

OBJECTIVE

The current multi-center study is aimed to evaluate if HELIOS (AESKU Diagnostics, Wendelsheim, Germany) contributes to comparability of ANA screening results among different labs，and establish application specification of HELIOS for standardization of ANA detection.

METHODS

ANA detection by manual IFA method and HELIOS on 230 clinical serum samples in eight laboratories. The performance to discriminate positive/negative screening results, endpoint titer estimation and pattern recognition were evaluated in HELIOS and manual visual.

RESULTS

The positive coincident rate for ANA detection by manual IFA ranges from 87.7% to 97.8%, the negative coincidence rate ranges from 68.8% to 100%, the correctly estimated titer evaluation were 80 to 171 cases, the correct pattern in 146 to 161 cases, respectively. The positive coincident rate of HELIOS for ANA detection ranges from 91.2% to 97.7%, the negative coincidence rate ranges from 96.5% to 100%, the correctly estimated titer evaluation were 145 to 157 cases, the correct pattern in 123 to 140 cases, respectively.

CONCLUSION

HELIOS could provide accurate diagnostic results, this include not only positive/negative results, but also endpoint titer, common patterns. The application of this system can help to promote standardization of ANA detection.

Recent Approaches To Optimize Laboratory Assessment of Antinuclear Antibodies

The presence of antinuclear antibodies (ANAs) is a hallmark of a number of systemic autoimmune rheumatic diseases, and testing is usually performed as part of the initial diagnostic workup when suspicion of an underlying autoimmune disorder is high. The indirect immunofluorescence antibody (IFA) technique is the preferred method for detecting ANAs, as it demonstrates binding to specific intracellular structures within the cells, resulting in a number of staining patterns that are usually categorized based on the cellular components recognized and the degree of binding, as reflected by the fluorescence intensity or titer. As a screening tool, the ANA patterns can guide confirmatory testing useful in elucidating a specific clinical diagnosis or prognosis. However, routine use of ANA IFA testing as a global screening test is hampered by its labor-intensiveness, subjectivity, and limited diagnostic specificity, among other factors. This review focuses on current efforts to standardize the nomenclature of ANA patterns and on alternative methods for ANA determination, as well as on recent advances in image-based computer algorithms to automate IFA testing in clinical laboratories.