The enzyme that cuts von Willebrand factor down to size.
ADAMTS13 cleaves the longest, most adhesive von Willebrand multimers as they unfold under shear. When activity falls below roughly 10%, those multimers persist and drive platelet-rich microthrombi — the picture of thrombotic thrombocytopenic purpura. A severe deficiency, in the appropriate clinical context, is what separates TTP from the other thrombotic microangiopathies and changes management. Technoclone's Technozym ADAMTS13 Activity ELISA, with matched antigen and inhibitor kits, is a manual reference-method ELISA for confirmatory and method-comparison work, not a rapid front-line emergency test — we advise on when it is the right call. Where turnaround drives the acute treatment decision, an automated CLIA such as the HemosIL AcuStar is the better choice; the Technozym assay earns its place on reference-method performance and the full antigen-and-inhibitor work-up.
Cleavage at a single bond — Tyr1605–Met1606.
ADAMTS13 recognises the von Willebrand A2 domain only once shear force has unfolded it, then scissors the exposed Tyr1605–Met1606 peptide bond. That single cut governs multimer size; lose the enzyme and the ultra-large multimers stay intact.
The cut at Tyr1605–Met1606, above an activity scale 0–100% with the <10% severe-deficiency line that defines TTP in context.
ADAMTS13 cleaves the unfolded von Willebrand A2 domain at the Tyr1605–Met1606 bond, yielding smaller multimers. On the activity scale (0–100%), a dashed line at 10% marks severe deficiency: an activity <10 IU/dL (<10%) is the hallmark of TTP when the clinical picture fits, the two readouts being interchangeable on the scale (Furlan 1996; Tsai 1996; ISTH 2020).
Severe deficiency <10 IU/dL (<10%) is the hallmark of TTP in the appropriate clinical context.
How the Technozym ELISA holds up against the reference and the automated comparator.
The fair comparison is on shared axes — correlation against the FRETS-VWF73 reference method and against the next-best automated platform, and each platform's own validated precision. The Werfen HemosIL AcuStar (CLIA) is the named automated comparator; FRETS-VWF73 is the reference assay.
Across 94 samples, the Technozym ADAMTS13 Activity ELISA correlated with the FRETS-VWF73 reference at r=0.92, and with the automated AcuStar at r=0.86 — close agreement with both the reference method and the automated comparator.
The figures here are for the Activity ELISA. We don't quote a Technozym IFU CV the manufacturer hasn't published — we'd rather leave the figure blank than cite one we can't stand behind. Activity is reported in IU/dL and as a percentage.
A smaller study put the Technozym ELISA against AcuStar at Pearson r=0.93, with a Bland–Altman bias of 2.54% (SD 6.38) and κ=0.82 for agreement on the <10% cut-off. The small sample size limits how much weight it carries — read it alongside Singh 2023, not instead of it.
Small cohort (n=24). No source URL is published for this study, so the citation is given as journal, volume and year only.
HemosIL AcuStar (Werfen) — automated CLIA
The AcuStar is the automated chemiluminescence assay most laboratories will weigh against the manual ELISA. On its own published merits it returns a first result in about 33 minutes (then roughly a minute per additional sample), with inter-assay CV of roughly 9.1–9.6% (intra-assay 3.3–5.5%), and for acute TTP reaches sensitivity 90.1% and specificity 99.7%. Where rapid turnaround drives the decision, that automation is a real advantage; where a laboratory already runs ELISA workflows, the Technozym assay sits naturally alongside them.
These are the AcuStar's own published figures, not a head-to-head against the Technozym ELISA; precision worsens at the low, TTP-range activity where the cut-off decision is actually made.
Severe deficiency <10 IU/dL — diagnostic of TTP in context
A measured ADAMTS13 activity below 10 IU/dL (≈<10%) is diagnostic of TTP in the right clinical setting, distinguishing it from the other thrombotic microangiopathies. The mechanism is specific: ADAMTS13 cleaves the von Willebrand A2 domain at Tyr1605–Met1606, and without that cut the ultra-large multimers persist.
The cut-off is a diagnostic threshold read in clinical context, not a stand-alone result; activity may be reported in IU/dL or as the equivalent percentage.
Activity, antigen and inhibitor — and a method matched to your laboratory.
A full ADAMTS13 work-up is rarely one number. Activity confirms or excludes the severe deficiency; antigen and inhibitor testing then separate congenital from acquired, immune-mediated disease — which changes treatment.
The Technozym assays
- Technozym ADAMTS13 Activity ELISA — colorimetric, the assay carrying the lead correlation data above.
- Antigen ELISA — distinguishes reduced production from accelerated clearance.
- Inhibitor assay — identifies acquired, autoantibody-mediated TTP.
Technofluor (fluorogenic) is also available; we hold no separate validation data for it.
What elixir does
As UK partner for Technoclone, we advise on which read-out and panel fit your throughput and case mix. We are candid about scope: the Technozym ELISA is a confirmatory, reference-laboratory method — its strengths are reference-method performance, antigen and inhibitor work-up, and method comparison. For an urgent TTP work-up, where rapid turnaround gates plasma exchange and caplacizumab, an automated CLIA such as the HemosIL AcuStar is the better front-line choice — and where that is the right answer for your turnaround, we say so.
Any structural or computational modelling we offer around assay design is a human-led service — scoped, run and signed off by a person — not a product on the shelf.
The figures on this page, and where they come from.
- Singh M, et al. Technozym ELISA vs FRETS-VWF73 r=0.92; vs AcuStar r=0.86 (n=94). RPTH 2023;7(2):100108. PMC10099301
- Stratmann J, et al. Technozym ELISA vs AcuStar Pearson r=0.93; Bland–Altman bias 2.54% (SD 6.38); κ=0.82 (n=24). J Thromb Thrombolysis 2020;50(3):628.
- Beranger N, et al. AcuStar — first result ~33 min (then ~1 min per additional sample), inter-assay CV 9.1–9.6% (intra 3.3–5.5%), acute-TTP sensitivity 90.1% / specificity 99.7%. RPTH 2021;5(1):81. PMC7845081
- Furlan M, et al. ADAMTS13 cleaves vWF at the Tyr1605–Met1606 bond within the A2 domain. Blood 1996;87:4223–34. (See also Tsai HM. Blood 1996;87:4235–44.)
- Kokame K, et al. FRETS-VWF73 fluorogenic substrate for the ADAMTS13 reference activity method. 2005. PMID 15801961
- ISTH 2020 guideline — severe deficiency <10 IU/dL (<10%) diagnostic of TTP in the appropriate clinical setting. PMC8146131
Pricing an ADAMTS13 panel, or weighing ELISA against automation?
Tell us your throughput, your case mix and the read-out your laboratory is set up for. We will reply with how we would approach the panel, what it would involve, and an honest quote — usually within two working days.