| Web: | mayocliniclabs.com |
|---|---|
| Email: | mcl@mayo.edu |
| Telephone: | 800-533-1710 |
| International: | +1 855-379-3115 |
| Values are valid only on day of printing | |
| Web: | mayocliniclabs.com |
|---|---|
| Email: | mcl@mayo.edu |
| Telephone: | 800-533-1710 |
| International: | +1 855-379-3115 |
| Values are valid only on day of printing | |
A 49-year-old female with FLT3+ AML became refractory to platelet transfusions 2 weeks after initiating chemotherapy with venetoclax, midostaurin, and corticosteroids. A solid phase single antigen bead (SAB) assay demonstrated the patient had an antibody to all HLA-B antigens sharing the Bw6 epitope. Subsequently, she was given IVIG to help bolster her platelet counts. A solid phase red blood cell adherence platelet crossmatch was performed and a unit homozygous for Bw4 class antigens was unexpectedly incompatible (image; right columns of wells). Repeat testing performed on a prior sample showed the unit was compatible (image; left columns of wells).
The correct answer is...
The correct answer is Assay interference by IVIG.
IVIG is manufactured by pooling plasma from a large number of donors, some of which can have HLA antibodies. The IVIG present in a patient’s sample can bind to the HLA antigens on the platelets utilized in a platelet crossmatch creating a positive (incompatible) result. Thus, the binding of HLA antibodies contained within the IVIG can cause an erroneously false positive crossmatch result. The other agents/drugs do not cause interference with the platelet crossmatch assay.
References
1. Immucor Capture-P® Solid Phase System for the Detection of IgG Antibodies to
Platelets package insert; version 340-14.
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Holly Berg, D.O. Resident, Anatomic and Clinical Pathology Mayo Clinic @DOPathGal |
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Justin Juskewitch, M.D., Ph.D. Senior Associate Consultant, Transfusion Medicine Mayo Clinic Assistant Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine and Science |
