Faculty Collaboration Database

A Novel PF4-Dependent Platelet Activation Assay Identifies Patients Likely to Have Heparin-Induced Thrombocytopenia/Thrombosis. Chest 2016 Sep;150(3):506-15

Date

02/26/2016

Pubmed ID

26905366

Pubmed Central ID

PMC5028397

DOI

10.1016/j.chest.2016.02.641

Scopus ID

2-s2.0-84995622136 (requires institutional sign-in at Scopus site)   77 Citations

Abstract

BACKGROUND: Almost without exception, patients with heparin-induced thrombocytopenia/thrombosis (HIT) have antibodies that recognize platelet factor 4 (PF4) in a complex with heparin; however, many heparin-treated patients without HIT are also antibody-positive. A platelet activation test, the serotonin release assay (SRA), is useful for identifying a subset of antibodies that are platelet-activating and most likely to cause HIT. However, this "gold standard" assay for HIT diagnosis is technically demanding and is routinely available only through referral laboratories, limiting its availability for timely diagnosis and management.

METHODS: We compared the diagnostic performance of the SRA with that of a technically simple platelet activation assay, the PF4-dependent P-selectin expression assay (PEA), which uses platelets pretreated with PF4 as targets for antibody detection. Archived serum samples from 91 patients for whom clinical information (HIT 4Ts [thrombocytopenia, timing of platelet count fall, thrombosis, and other causes of thrombocytopenia] score) was available were used. Patients with an intermediate 4Ts score and a PF4 ELISA (enzyme-linked immunosorbent assay) optical density ≥ 2.0, or a high 4Ts score and a PF4 ELISA optical density ≥ 1.0, were considered HIT positive; others were designated HIT negative.

RESULTS: The PEA had higher diagnostic accuracy (area under the curve, 0.92 vs 0.82; P = .02) than the SRA, using this definition of HIT. Eleven of 16 serum samples that were PEA positive and SRA negative were HIT positive. Studies done with identical target platelets and serially diluted samples from patients with HIT showed that the PEA is inherently more sensitive than the SRA for the detection of platelet-activating antibodies.

CONCLUSIONS: The PEA is technically less demanding than the SRA and may be more accurate for the diagnosis of HIT.

Author List

Padmanabhan A, Jones CG, Curtis BR, Bougie DW, Sullivan MJ, Peswani N, McFarland JG, Eastwood D, Wang D, Aster RH

Authors

Brian Curtis PhD Director in the Platelet & Neutrophil Immunology Laboratory department at BloodCenter of Wisconsin
Demin Wang PhD Professor in the Microbiology and Immunology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adult
Aged
Aged, 80 and over
Anticoagulants
Autoantibodies
Case-Control Studies
Enzyme-Linked Immunosorbent Assay
Female
Heparin
Humans
Male
Middle Aged
P-Selectin
Platelet Activation
Platelet Factor 4
Thrombocytopenia
Thrombosis