Comparison of Solid-Phase Antibody Screening Tests with Pooled Red Cells in Blood Donors

Solid-phase systems are very sensitive for detection of erythrocyte alloantibodies in serum and suitable for large scale donor screening. Serum samples of 10,008 blood donors were screened by three solid-phase tests (Capture R Ready Screen, Solidscreen II, and Solidscreen II-Donor) with pooled red cells derived from two donors. The prevalence of antierythrocyte IgG and IgM antibodies in donor sera was 0.56% (IgG antibodies: 0.42%). The test efficiency for IgG antibodies was 1.40 with Capture R Ready Screen (test sensitivity 97.6%, test specificity 99.39%), 1.78 with Solidscreen II (95.1, 99.88%), and 1.95 with Solidscreen II-Donor (92.7, 99.98%). The IgG antibody titers differed significantly between all tests including a gel matrix test: Capture R > ID-Gel > Solidscreen II > Solidscreen II-Donor. Previously characterized antibodies that were not detected after long-term follow-up by any of the three solid-phase tests had a prevalence of 0.10%. All three solid-phase tests detected the alloantibodies, which were of higher titers and considered clinically relevant in blood components. The significant difference in antibody titers between the tests was not matched by a similar variance in the detection of donors with antibodies. Even with sensitive solid-phase tests, many antibodies may not be detected after long-term follow-up.