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No single assay is sufficient to fully detect the breadth of autoantibody biomarkers observed in systemic autoimmune disease. Although IFA testing on the HEp-2/2000® assay remains the gold standard for screening of antinuclear autoantibodies, some patterns can still indicate multiple possible autoantibodies. Additionally, some labs are not equipped for initial screening of slide assays or need multiple options to meet their high-throughput needs.
For this reason, most laboratories rely on a combination of broad screening assays and targeted follow-up tests to achieve clinically meaningful results.
The RELISA® (Reliable Enzyme-Linked Immunosorbent Assay) product line offers a suite of enzyme immunoassays designed to support this approach.
In this bulletin, we will review the complete catalog of Immuno Concepts RELISA® assays, with emphasis on their intended use, antigen composition, and role within a structured testing algorithm.
While ANA IFA testing can identify the patterns associated with the ENA Antigens, many labs still prefer a second high-throughput screen to confirm the presence of ENA autoantibodies.
The RELISA® ENA Single Well Screening Kit is intended as a reflex screening tool for the detection of common extractable nuclear antigen (ENA) antibodies. Each microtiter well contains a defined mixture of six antigens: Sm, RNP, SSA/Ro (60/52kDa), SSB/La, Scl-70, and Jo-1. These represent the “classical” and most frequently encountered ENA specificities in clinical practice.
The primary utility of this assay lies in its ability to rapidly exclude ENA-negative samples, thereby reducing the need for more resource-intensive multiparameter testing. In this context, the assay functions as an efficient intermediate step between broad ANA screening and detailed antibody characterization.
The RELISA® ENA Multiparameter Kit is designed for the qualitative identification of individual ENA antibodies, including SSA/Ro (60/52kDa), SSB/La, Sm, Sm/RNP, Scl-70, and Jo-1. As mentioned above, it is the logical follow-up to a positive ENA Single Well Screen result, or an ANA pattern with a high probability of ENA antigen association (IE, AC-4/5 speckled).
Unlike screening assays, this system allows for the discrete evaluation of each ENA antigen separately. As each of these antibodies is strongly associated with specific autoimmune conditions, narrowing a positive screen down to a single result is valuable diagnostic information.
By identifying a specific autoantibody, the RELISA® ENA Multiparameter Kit can help accelerate diagnosis and allow for the targeted treatments that give the best possible patient outcomes.
While ANA IFA testing on HEp-2/2000® remains the gold standard for screening, some labs prefer an alternative method for the first round of tests. The RELISA® ANA Screen is a high-sensitivity screening assay for detecting autoantibodies directed against a wide range of nuclear and cytoplasmic antigens.
On this assay, microwells are coated with a mixture of stabilized antigens, including dsDNA, histones, SSA/Ro (60/52kDa), SSB/La, Sm, Sm/RNP, Scl-70, centromere, Jo-1, PCNA, ribosomal P, M2, as well as additional antigens derived from HEp-2 cellular extracts.
Because this assay includes a broad spectrum of nuclear and cytoplasmic antigens, it can detect reactivity that may not be identified with more targeted antigen panels, such as the RELISA® ENA Single Well Screen. As such, the RELISA® ANA Screen is well-suited for initial screening, particularly in workflows where high throughput is especially valued.
The RELISA® MPO and PR3 assays are designed for confirm anti-neutrophil cytoplasmic autoantibodies (ANCA).
These assays detect antibodies directed against myeloperoxidase (MPO) and proteinase 3 (PR3), the two principal antigens associated with ANCA-related vasculitides. While IFA testing on ethanol and formalin-fixed neutrophil slides is the preferred screening method for ANCA, this antigen-specific assay provides a confirmatory result that supports the final interpretation.
Detection of MPO-ANCA and PR3-ANCA supports the diagnosis of microscopic polyangiitis and granulomatosis with polyangiitis, respectively. As such, these assays play a critical role in confirmatory testing and clinical correlation.
The RELISA® Cardiolipin Kit is an isotype-specific assay for quantifying IgG and IgM anti-cardiolipin antibodies.
Anti-cardiolipin antibodies are one of the primary serologic markers associated with antiphospholipid syndrome (APS), and may be detected in patients presenting with thrombotic events, recurrent pregnancy loss, or other clinical features consistent with antiphospholipid antibody-related disease.
By including multiple antibody isotypes (IgG and IgM), different disease correlations can be predicted. Additionally, given the variability in antibody expression across patients, testing both isotypes improves the assay’s overall sensitivity.
The RELISA® Anti-dsDNA assay is an enzyme immunoassay designed for the detection of antibodies to double-stranded DNA.
While other methods exist for detecting anti-dsDNA antibodies, such as Crithidia luciliae IFA testing or the presence of a Homogeneous pattern on ANA tests, an ELISA-based assay remains a valuable tool for labs that find it fits best within their existing workflow.
Additionally, as anti-dsDNA antibodies are strongly associated with SLE and may correlate with disease activity, many clinicians repeat testing to track a patient’s response to treatment. While a titer endpoint can also be used for such longitudinal monitoring, some studies prefer the numerical “IU/mL” unit for data consistency.
The RELISA® product line includes multiple assays to cover essential testing needs:
By integrating these assays into a structured testing algorithm, laboratories can improve both diagnostic accuracy and operational efficiency, while ensuring that clinically relevant autoantibody profiles are not overlooked.
~Peter Rucker, Technical Specialist – Immuno Concepts
Immuno Concepts, NA Ltd.
9825 Goethe
Ste 350
Sacramento, CA 95827
Office: 916-363-2649
Fax: 916-363-2843
Tech Support: 800-251-5115
Ordering: 800-405-3600