Platelet Crossmatch By Flow Cytometry : Evaluation And Feasibility Study
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Date
2015-08
Authors
Yahya, Nurul Munira
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Managing patient with immune mediated platelet refractoriness can be very challenging. One of the approach is by selecting compatible platelet via crossmatch test. The existing protocol ; Solid Phase Red Cell Adherence (SPRCA) assay works very well as a platelet crossmatch assay. However, it have some limitations that make it unsuitable to be used in certain situation. SPRCA is a fully manual test with manual result interpretation and documentation. It utilizes U-shape microplate and run on batches of samples. Due to manual operation and laborious procedure, there are chances of bias to occur, therefore competency and skill of operator becomes an important confounding factor. Furthermore, SPRCA is not suitable for single or low throughput crossmatch. Due to these restrictions, there is a need to search for another platelet crossmatch protocol that can overcome the limitations of SPRCA thus be implemented in blood centre setting. Platelet Immunofluorescence Test (PIFT) assay is an assay that runs on similar principle (whole platelet based assay) as SPRCA, except that it utilizes flow cytometer for result analysis. In this study, PIFT is being challenged to discover its strength and advantages in performing platelet crossmatch test, particularly on qualitative performance and feasibility aspect on operational service. 20 platelet apheresis donors were enrolled in this study and their HPA genotype were determine by PCR-SSP. 11 known control serums from 4 category of platelet reactive antibodies were recruited and antibody specificity were determined. Crossmatch were performed on freshly prepared donor’s platelet suspension against serum. Each crossmatch were then repeated once either on day-1, day-2 or day-3 of platelet suspension preparation. The predicted compatibility of donor crossmatched to serum were established based on the donor’s genotype and antibody specificity, and were compared to the actual crossmatch result obtained. Compatible and incompatible observation were then translated as true and false of positive and negative outcomes. The results were then statistically analysed with parameters suited for qualitative binomial data. From all 20 donors and 11 serums, 237 total crossmatching have been performed. In detecting incompatibility, PIFT has demonstrated the ability to detect as high as 91.2%, with accuracy of 62.4% and false positive of 34.2%. Conversely, when detecting compatibility, it detects only 65.8% with the accuracy as high as 93.2% with low false negative of 8.8%. This shows an outstanding performance of crossmatching test where it detect more false positive to enhance safety, in the same time gives accurate compatible result. Furthermore, PIFT can be done with single or low throughput crossmatch, and able to generate computer-based-results which a feature that is lacking in SPRCA. PIFT cost about RM3.50 per test. It is a simple, cheap and reliable assay. PIFT shows an outstanding performance as a platelet crossmatch assay. It offers great advantages and are feasible to be implemented in a blood banking setting for the provision of compatible platelet supply for the immune mediated thrombocytopenic patient.
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Keywords
Platelet