Alloantibodies are clinically relevant. In vitro antibody detection tests (screening) are used to detect the presence of these antibodies in patient and donor sera or plasma. In some regions, diluted plasma or serum samples have to be tested as an additional secondary test. The aim of this study was to establish and evaluate the performance of a set of newly developed automated dilution screening assays compared to semi-automated method for IgG screening.

Fully automated 1:10 and 1:50 dilution assays were developed to screen diluted serum or plasma samples for unexpected IgG antibodies against red blood cells. The assays are based on solid phase Capture® technology for the NEO Iris® and NEO® v2.0 automated platforms. Patient, pregnancy and donor samples with different known alloantibodies as well as the 3rd WHO international standard for anti-D immunoglobulin as a reference were tested. All samples were analyzed to determine result concordance of the two fully automated 1:10 or 1:50 sample dilution screening assays to manual sample dilutions, respectively, followed by automated IgG antibody detection on another IgG screening assay without automated dilution.

In total, 209 samples (total number of tests: 209 * 3 = 627 tests, as each sample is tested with three different screening cells) were tested on both assays that diluted the samples on the instrument and compared to results obtained from manual 1:10 or 1:50 sample dilution, respectively tested on another IgG screening assay. For both dilution screening assays, all analyzed samples within this study showed 100% concordance and achieved 99.5% agreement at the 95% lower bound confidence interval after retesting and excluding persistent equivocal results.

Automated screening assays for the detection of IgG alloantibodies with sample dilutions of 1:10 and 1:50 enable efficient and accurate detection in transfusion medicine and fulfill the region-specific requirements as an additional method.

No conflict of interest to declare.