Multicentre evaluation of the new ORTHO VISION® analyser

Multicenter evaluation of a high-throughput microarray platform for extensive red blood cell phenotyping and antibody screening

BACKGROUND

Blood typing and antibody screening are key elements of transfusion safety. However, available single platform, flexible, and affordable technologies are limited, especially for extended phenotyping. Microarray-based technology allows for this extended phenotyping with the flexibility of piecemeal analysis.

STUDY DESIGN AND METHODS

This study was conducted in three blood donor laboratories to determine the performance of a high-throughput microarray-based system for ABO, RH1-RH5, and KEL1 typing, ABS and extended phenotyping (RH8, KEL2&3, FY1&2, JK1, MNS3). Specimens were tested simultaneously on local platforms and on the microarray-based system. When discrepancies were identified, resolver testing were performed.

RESULTS

In total, 4862 blood samples were tested for standard phenotype, 4257 for antibody screening and 2194 for extended phenotype. Results were available for 92.12% of the samples. The overall percent agreements were: 100% for ABO, 99.8% for RH1, 99.24% for RH2-5 and 99.86% for KEL1, 93.16% for antibody screening, and 99.68% for extended phenotype.

CONCLUSIONS

This microarray-based system provides highly comparable results to current CE marked assays. The ability to continuously test 3000 microarrays in 1 day, providing simultaneously both extended RBC phenotyping and antibody detection drives laboratory efficiencies. The results of our study validate the performance of this new technology; however, the percentage of samples without results must be reduced and further analysis is required to interpret the ABS screening performances. This could constitute a real breakthrough in transfusion, making it possible in the long term, on a single platform, to carry out all the analyses necessary for the qualification of donations.

Evaluating automated titre score as an alternative to continuous flow analysis for the prediction of passive anti-D in pregnancy

OBJECTIVES

To evaluate the potential of the automated titre score (TS) as an alternative method to continuous flow analysis (CFA) for the prediction of the nature of anti-D in pregnancy.

BACKGROUND

The 2016 revised British Society for Haematology (BSH) antenatal guidelines recommended a measurement of anti-D concentration by CFA to ensure the detection of potential immune anti-D. Due to high referral costs and resource pressures, uptake has been challenging for hospital laboratories. Serious Hazards of transfusion (SHOT) data have previously shown that this has contributed to missed antenatal follow ups for women with immune anti-D and neonates affected by haemolytic disease of the fetus/newborn.

METHODS/MATERIALS

In this multicentre comparative study, samples referred for CFA quantification were also tested by an ORTHO VISION automated anti-D indirect antiglobulin test (IAT) serial dilution and then converted to TS. CFA results and history of anti-D prophylaxis were used to categorise samples as passive or immune, with the aim of determining a potential TS cut-off for CFA referral of at risk patients.

RESULTS

Five UK National Health Service (NHS) trusts generated a total of 196 anti-D TS results, of which 128 were classified as passive and 68 as immune. Diagnostic testing of CFA and TS values indicated a TS cut-off of 35 to assist in distinguishing the nature of anti-D. Using this cut-off, 175 (89%) results were correctly assigned into the passive or immune range, giving a specificity of 92.19% and a negative predictive value of 91.47%.

CONCLUSION

TS in conjunction with clinical and anti-D prophylaxis history can be used as a viable and cost-effective alternative to CFA in a hospital laboratory setting.

Blood group alters platelet binding kinetics to von Willebrand factor and consequently platelet function

Blood type O is associated with a lower risk of myocardial infarction. Platelets play a critical role in myocardial infarction. It is not known whether the expression of blood group antigens on platelet proteins alters platelet function; we hypothesized that platelet function would be different between donors with blood type O and those with non-O. To address this hypothesis, we perfused blood from healthy type O donors (n = 33) or non-O donors (n = 54) over pooled plasma derived von Willebrand factor (VWF) protein and purified blood type-specific VWF at arterial shear and measured platelet translocation dynamics. We demonstrate for the first time that type O platelets travel farther at greater speeds before forming stable bonds with VWF. To further characterize these findings, we used a novel analytical model of platelet interaction. Modeling revealed that the kinetics for GPIb/VWF binding rate are significantly lower for type O compared with non-O platelets. Our results demonstrate that platelets from type O donors interact less with VWF at arterial shear than non-O platelets. Our results suggest a potential mechanism for the reduced risk of myocardial infarction associated with blood type O.