PF4-Dependent Immunoassays in Patients with Vaccine-Induced Immune Thrombotic Thrombocytopenia: Results of an Interlaboratory Comparison.
Thromb Haemost
; 121(12): 1622-1627, 2021 12.
Article
in English
| MEDLINE | ID: covidwho-1334018
ABSTRACT
BACKGROUND:
Coronavirus disease 2019 vaccine ChAdOx1 nCov-19 may rarely lead to vaccine-induced thrombotic thrombocytopenia (VITT). Antibody-mediated, platelet factor 4 (PF4)-dependent platelet activation appears to resemble a key mechanism in VITT, partially comparable to heparin-induced thrombocytopenia. The use of PF4/heparin immunoassays has been proposed as part of a diagnostic approach, but their sensitivity has not been established.METHODS:
Sera from 12 well-defined VITT patients were first studied by two different laboratories in functional assays. Sera where then used for an interlaboratory comparison, in which five different PF4/heparin immunoassays were used by four laboratories.RESULTS:
Results for functional testing were highly concordant. VITT antibodies were also reliably detected by PF4/heparin enzyme-linked immunosorbent assays (ELISAs) (92-100%). In contrast, only 25% of VITT antibodies were reactive in a particle gel immunoassay (PaGIA), and 8% in a lateral flow assay (LFA). An automated chemiluminescence immunoassay (CLIA) was negative for all sera tested (0%).CONCLUSION:
It seems feasible to establish functional antibody testing for the confirmation of VITT. For the initial screening of suspected VITT cases, PaGIA, LFA, and CLIA are useless when applied as single tests. Only ELISA-based PF4/heparin immunoassays are sensitive enough to be incorporated in the diagnostic workup. However, a combination of a positive ELISA and a negative CLIA may be useful to identify VITT antibodies in the absence of confirmatory functional assays.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Platelet Factor 4
/
Enzyme-Linked Immunosorbent Assay
/
Vaccination
/
Purpura, Thrombocytopenic, Idiopathic
/
ChAdOx1 nCoV-19
/
Antibodies
Type of study:
Diagnostic study
/
Prognostic study
Topics:
Vaccines
Limits:
Humans
Language:
English
Journal:
Thromb Haemost
Year:
2021
Document Type:
Article
Affiliation country:
A-1535-9002
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