Thermo Fisher Scientific has announced an expansion of its LABScreen Single Antigen ExPlex Portfolio with the introduction of LABScreen Single Antigen HLA Class II ExPlex – Group 2, a new panel designed to extend HLA-DQ coverage for histocompatibility and immunogenetics laboratories managing complex transplant cases. The addition brings the total HLA-DQ antigen and heterodimer panel from 24 beads to 51, and enables assessment of up to 146 Class II Single Antigen Beads within a single well. The product is CE-marked and available now in the European Union under IVDR; it is not currently available in the United States or Canada.
Why HLA-DQ antibodies are becoming harder to ignore
For much of transplant diagnostics history, antibody testing concentrated on HLA-A, HLA-B, and HLA-DR, the loci historically used for organ allocation. HLA-DQ received comparatively less attention, partly because early testing technology offered limited resolution at that locus, and partly because the clinical significance of DQ-specific donor-specific antibodies (DSA) took longer to establish in the literature.
That picture has shifted considerably. A 2025 review published in Frontiers in Immunology found that HLA-DQ mismatches significantly impact the development of donor-specific antibodies and transplant outcomes, and that HLA-DQ antibodies are highly immunogenic and detrimental, requiring advanced high-resolution HLA typing to improve mismatch assessment and clinical risk evaluation. The same review noted that traditional serological or low-resolution typing often misclassifies mismatches, leading to inaccuracies in predicting outcomes.
The eplet-level picture is equally compelling. A 2025 PMC analysis found that high eplet mismatch loads, particularly at HLA-DQ, are strongly associated with de novo donor-specific antibody development, antibody-mediated rejection, and reduced graft survival. For histocompatibility labs fielding increasingly sensitized patients and navigating a more ethnically diverse global donor pool, narrower DQ panels can leave meaningful antibody reactivity undetected.
Real-world experience underscores the gap. A case series from the University Health HLA Laboratory in San Antonio demonstrated that adding the ExPlex panel to a standard single-antigen bead workflow enabled detection of HLA reactivity that would otherwise have gone undetected, without requiring additional tests. The lab cited its growing Hispanic patient population as a key driver: ethnic diversity introduces HLA allele frequencies not well-represented in foundational bead panels, and missing those specificities can compromise virtual crossmatch accuracy.
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What the new LABScreen ExPlex Group 2 panel adds
The LABScreen Single Antigen platform, developed by One Lambda (now part of Thermo Fisher Scientific following a 2012 acquisition), has long been a reference standard for HLA antibody identification. Single antigen beads allow for a precise, highly sensitive determination of a patient's HLA antibody profile, making discrimination between donor-specific and non-donor-specific antibodies possible. The ExPlex line extended that capability by pairing the original assay with an additional bead set in the same well, increasing total antigen coverage without adding process steps.
The new Group 2 panel deepens that approach specifically at the HLA-DQ locus:
| Feature | Existing ExPlex Class II | New Group 2 extension |
|---|---|---|
| HLA-DQ antigens and heterodimers | 24 beads | +27 beads (total: 51) |
| Max Class II SABs in a single well | 119 | Up to 146 |
| Additional workflow impact | None | None |
| Regulatory status (EU) | CE-marked (IVDR) | CE-marked (IVDR) |
| US/Canada availability | Not available | Not available |
The new panel integrates directly into existing LABScreen Single Antigen workflows on the LABScan3D instrument, requiring no additional staff retraining, no workflow modifications, and no capital investment in new instrumentation.
Key features and benefits include:
- Expanded HLA-DQ coverage: 27 new HLA-DQ antigens and heterodimer combinations, bringing the DQ-specific bead count to 51 in the extended ExPlex panel
- High Class II multiplexing: Up to 146 Class II Single Antigen Beads assessable in a single well, supporting broad antibody profiling in sensitized patients
- No workflow disruption: Direct integration into established LABScreen Single Antigen procedures, with no additional time required after assay setup
- Eplet analysis support: Broader bead coverage facilitates evaluation of eplet patterns that inform molecular matching decisions
- Operational efficiency: Compatible with existing LABScan3D instrumentation; no new equipment investment required
"HLA-DQ antibodies have become an area of increasing clinical focus, with growing evidence linking them to transplant rejection," said Dave Lowe, senior director, research and development, transplant diagnostics, Thermo Fisher Scientific. "By expanding HLA-DQ coverage within an existing workflow, laboratories can support better-informed matching decisions before transplant and more comprehensive monitoring after, where earlier detection of donor-specific antibodies can make a meaningful difference for patients."
Who benefits from broader HLA-DQ panel coverage
The intended audience for this expansion cuts across several stakeholder groups in the transplant ecosystem. Histocompatibility and immunogenetics laboratories managing increasingly complex antibody profiles are the primary users. These are the labs receiving sensitized patients who have been immunized through prior transplants, pregnancies, or transfusions, and who carry pre-formed antibody specificities against a wide range of HLA antigens. For these high-PRA (panel-reactive antibody) patients, granular antibody identification is not an academic exercise: it directly determines which donors can be safely considered for a match.
Transplant laboratory directors evaluating panel coverage against a diversifying global HLA database will also find the Group 2 expansion relevant. As donor pools broaden and patient demographics shift, standard antigen panels built on historically predominant HLA allele distributions can leave gaps. A single-center experience at the University Health HLA Laboratory in San Antonio demonstrated that adding the ExPlex panel allowed detection of HLA reactivity that would previously have gone undetected, without requiring additional tests, thereby saving time and resources.
For transplant clinicians, the downstream value is clearer crossmatch data. When an HLA-DQ antibody is present but not detected pre-transplant, the result can be a positive crossmatch after the fact, or a rejection episode that might have been anticipated. Post-transplant, the same coverage gap can result in de novo DQ-DSA being missed until graft function has already begun to decline.
Workflow integration and operational considerations for lab managers
One of the more practically significant aspects of the new panel is how little it asks of laboratory operations. Labs running the LABScreen Single Antigen workflow on the LABScan3D platform can incorporate the Group 2 extension without modifying their SOP, retraining staff, or procuring new instrumentation. The ExPlex format uses a single-well, combined-bead approach: the expanded DQ antigens are assessed in the same assay run as the existing panel components, with no additional time required after setup.
For lab managers weighing adoption, the more relevant operational questions are likely around data interpretation rather than workflow mechanics. The broader the bead panel, the more antibody specificities appear in results, and the more clinical context is needed to assign significance to each reactivity. Labs moving toward eplet-based reporting should evaluate whether their current analysis software supports the expanded bead library, and whether their clinical teams are prepared to act on the additional data.
The Frontiers in Immunology 2025 review cited above noted that while molecular mismatch analysis is increasingly associated with better outcomes, prospective evidence for its systematic use in organ allocation remains limited. Expanded antibody panel coverage and molecular mismatch analysis serve different but complementary functions; the ExPlex Group 2 panel addresses the antibody detection side of that equation.
What expanded HLA-DQ coverage means for your transplant lab
Thermo Fisher's move to deepen HLA-DQ coverage in the ExPlex portfolio reflects where the histocompatibility field is heading: more granular antibody characterisation, more attention to loci previously considered secondary, and an increasing expectation that labs can handle complex, sensitized patients without compromising turnaround time. Transplant diagnostics more broadly has moved toward earlier and more comprehensive biomarker detection, with multiple platforms seeking to identify rejection signals before clinically significant graft dysfunction develops.
For histocompatibility labs operating in the EU, the Group 2 expansion is available now under IVDR regulatory authorisation. Labs in the US and Canada will need to monitor for separate regulatory clearance; Thermo Fisher has not announced a timeline for that at this stage.
For the transplant lab manager evaluating whether to adopt, the essential calculus is clinical: how many of your patients have HLA-DQ sensitisation that your current panel may be undercharacterising? If the answer is uncertain, the Group 2 expansion provides a defined, low-disruption way to find out.
References
Das R, Greenspan NS. Understanding HLA-DQ in renal transplantation: a mini-review. Frontiers in Immunology. 2025;16:1525306. https://doi.org/10.3389/fimmu.2025.1525306
Lee H, et al. Clinical significance of HLA-DQ antibodies in the development of chronic antibody-mediated rejection and allograft failure in kidney transplant recipients. Medicine. 2016;95(12):e3094. https://pmc.ncbi.nlm.nih.gov/articles/PMC4839928/
Bezstarosti S, et al. Eplet mismatch analysis in kidney transplantation: from concept to clinical practice. PMC. 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12521851/
