Plasma exchange to remove HIT antibodies: dissociation between enzyme-immunoassay and platelet activation test reactivities

Repeated therapeutic plasma exchange (TPE) has been advocated to remove heparin-induced thrombocytopenia (HIT) IgG antibodies before cardiac/vascular surgery in patients who have serologically-confirmed acute or subacute HIT; for this situation, a negative platelet activation assay (eg, platelet ser...

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Bibliographic Details
Published in:Blood 2015-01, Vol.125 (1), p.195-198
Main Authors: Warkentin, Theodore E., Sheppard, Jo-Ann I., Chu, F. Victor, Kapoor, Anil, Crowther, Mark A., Gangji, Azim
Format: Article
Language:English
Subjects:
Aged
Blood Platelets - metabolism
Carcinoma - complications
Female
Hemorrhage
Heparin - adverse effects
Humans
Immunoenzyme Techniques - methods
Immunoglobulin G - chemistry
Kidney Neoplasms - complications
Plasma Exchange - methods
Platelet Activation - drug effects
Platelet Factor 4 - metabolism
Thrombocytopenia - chemically induced
Thrombosis - therapy
Treatment Outcome
Vena Cava, Inferior - pathology
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Summary:Repeated therapeutic plasma exchange (TPE) has been advocated to remove heparin-induced thrombocytopenia (HIT) IgG antibodies before cardiac/vascular surgery in patients who have serologically-confirmed acute or subacute HIT; for this situation, a negative platelet activation assay (eg, platelet serotonin-release assay [SRA]) has been recommended as the target serological end point to permit safe surgery. We compared reactivities in the SRA and an anti-PF4/heparin IgG-specific enzyme immunoassay (EIA), testing serial serum samples in a patient with recent (subacute) HIT who underwent serial TPE precardiac surgery, as well as for 15 other serially-diluted HIT sera. We observed that post-TPE/diluted HIT sera—when first testing SRA-negative—continue to test strongly positive by EIA-IgG. This dissociation between the platelet activation assay and a PF4-dependent immunoassay for HIT antibodies indicates that patients with subacute HIT undergoing repeated TPE before heparin reexposure should be tested by serial platelet activation assays even when their EIAs remain strongly positive. •Repeated plasma exchange removes sufficient HIT-IgG to achieve negative SRA despite ongoing strong-positive EIA.•Serially-diluted HIT sera tested in both SRA and EIA show that SRA negativity can be achieved with minimal decrease in EIA reactivity.
ISSN:0006-4971
1528-0020
DOI:10.1182/blood-2014-07-590844