Review of the problems involved in using enzymes in blood group serology--provision of freeze-dried ICSH/ISBT protease enzyme and anti-D reference standards. International Council for Standardization in Haematology. International Society of Blood Transfusion

Performance evaluation study of ID CORE XT, a high throughput blood group genotyping platform

BACKGROUND

Traditionally, red blood cell antigens have been identified using serological methods, but recent advances in molecular biology have made the implementation of methods for genetic testing of most blood group antigens possible. The goal of this study was to validate the performance of the ID CORE XT blood group typing assay.

MATERIALS AND METHODS

One thousand independent samples from donors, patients and neonates were collected from three research institutes in Spain and the Netherlands. DNA was extracted from EDTA-anticoagulated blood. The data were processed with the ID CORE XT to obtain the genotypes and the predicted blood group phenotypes, and results were compared to those obtained with well-established serological and molecular methods. All 1,000 samples were typed for major blood group antigens (C, c, E, e, K) and 371-830 samples were typed for other antigens depending on the rarity and availability of serology comparators.

RESULTS

The incorrect call rate was 0%. Four "no calls" (rate: 0.014%) were resolved after repetition. The sensitivity of ID CORE XT for all phenotypes was 100% regarding serology. There was one discrepancy in E- antigen and 33 discrepancies in Fy^b- antigen. After bidirectional sequencing, all discrepancies were resolved in favour of ID CORE XT (100% specificity). ID CORE XT detected infrequent antigens of Caucasians in the sample as well as rare allelic variants.

DISCUSSION

In this evaluation performed in an extensive sample following the European Directive, the ID CORE XT blood genotyping assay performed as a reliable and accurate method for correctly predicting the genotype and phenotype of clinically relevant blood group antigens.

Evaluation of Erytra® fully automated analyser for Routine Use in Transfusion Laboratory

OBJECTIVE

To evaluate efficiency and performance of Erytra® analyser in comparison to the reference platform of the NBT immunohaematology laboratory (Bio-Rad ID-System).

BACKGROUND

Moving to automation or semi-automation is a major focus of transfusion centres. The Erytra® (Grifols) is a new fully automated walk-away analyser with high volume processing capacity for pre-transfusion testing, designed to be used with the unique 8-column DG Gel® cards.

STUDY DESIGN AND METHODS

A total of 2201 immunohaematological tests (1041 ABO/D grouping, 1041 antibody screening, 51 antibody identification, 45 newborns (ABO/D and DAT) and 23 crossmatches were performed on 1160 donor/patient whole blood samples. Erytra®'s performance was assessed by means of a stress test replicating the routine work of a hospital laboratory.

RESULTS

Concordant results between the Erytra® and the reference method were obtained in 2195 (99·73 %) of the tests. There were only three discrepancies out of 6246 reactions (0·05%) in ABO/D grouping, all in the reverse group which did not mislead to group identification. Of the 1041 samples screened for antibody presence, Erytra® detected all the relevant antibodies [9 not detected weak prophylactic anti-D were determined to be clinically nonsignificant (<0·1 IU mL(-1) )] while Bio-Rad ID-System missed one anti-e and one anti-Jk(a) . Concordance for D grouping, crossmatching and newborns was 100%. Results of the simulated stress test exercise highlighted the capacity of Erytra® for absorbing into 4 h workloads equivalent to 24 h of routine.

CONCLUSIONS

Grifols' Erytra® analyser showed reliable high sensitivity, velocity and capacity to cope with high workload in the immunohaematology laboratory routine.

Evaluation of a modified IAT-gel with polyethylenglycol (PEG) addition method for red blood cell antibody identification

We aimed to evaluate whether a PEG-IAT method, modified for gel technique, could replace the two-stage enzyme method for routine identification of red blood cell (RBC) antibodies.A total of 161 selected patient samples were analyzed with the two-stage enzyme tube technique and the PEG-IAT in gel techniques. In 65 samples, identical antibody results were obtained by the two methods. An additional 28 antibodies were identified by either the PEG-IAT gel method or the enzyme method. Twenty antibodies were identified by the PEG-IAT gel method only (12 Rh antibodies, four anti-Kell, two anti-Fya, two anti-Jka), and eight antibodies by the enzyme method only (four Rh antibodies, one anti-K, one anti-Jka, two anti-Lea). The results in the remaining 68 samples were judged as nonspecific reactions, which were more common when the enzyme method was used. We concluded that the PEG-IAT in gel method identifies more RBC antibodies with less nonspecific reactions than the two-stage enzyme technique. However, no single method detected all clinical significant RBC antibodies.

New technologies for red-cell serology

Until 1943, blood-grouping tests were performed mainly on glass slides or tiles but, following the description of the antiglobulin test, tube techniques became widespread. With increasing workloads and pressure to be ever more cost-efficient, other 'reaction vessels' such as microplates have been developed for blood-group serological testing. The indirect antiglobulin test has been shown to be the most effective and reliable method for detecting clinically significant antibodies. As a result, this test has been developed, for example by the introduction of enhancement media such as low-ionic-strength saline and polyethylene glycol. However, the problems and inconvenience associated with the labelling and washing of large numbers of tubes were not overcome until the introduction of the solid-phase antiglobulin test and the newer microtubes containing gel or glass microbeads. These techniques are now replacing the conventional tube tests, but they too have their own limitations. There is still no single technique that will detect all clinically significant red-cell antibodies. Therefore, the safe transfusion of red cells that would survive optimally in the recipient depends not on a single test but on a series of tests and procedures, such as correct patient identification, blood-grouping, antibody-screening and compatibility-testing.