Recombinant blood group antigens in patient testing

Background

Antibodies to high-prevalence red cell antigens can be challenging in serologic patient workup. Hemagglutination inhibition assays using recombinant blood group antigens (rBGAs) can identify the specificity of the antibody and uncover additional, possibly significant, alloantibodies. Data of use in routine immunohematologic laboratories are still scarce. We report the use of rBGAs in patient testing regarding feasibility, effectiveness and limitations.

Methods

Patients (n=12) with suspected or known antibodies to high-prevalence antigens were tested with single soluble rBGAs (Ch, Rg, Kn^a, JMH, Yt^a, Do^b, CROM/DAF, Kell-Kp^b-Js^a, Cellano-Kp^b-Js^a, Lu^b/Au^b, Sc1; inno-train Diagnostic GmbH, Kronberg, Germany) according to the manufacturer's instruction. 2 µl rBGA solution was mixed with 25 µl patient plasma, incubated at room temperature for 30 min and tested in a gel agglutination system (BioRad ID-System) in the indirect antiglobulin test with untreated or papain-treated test cells. Inhibition of reactivity occurred if the corresponding antibody was present and additional antibodies could further be identified in routine test systems. Choice of rBGAs was dependent on preceding serologic results.

Results

In 9 (75%) of 12 patients antibodies to high-prevalence antigens were identified with rBGAs of the specificities Ch (n=3), Yt^a (n=3), Kn^a (n=2), and Lu^b (n=1). Single or multiple additional underlying antibodies of 6 different specificities (Wr^a, Fy^a, C, Jk^b, Fy^b, and S) were identified in 4 (44%) of these 9 patients. In 3 cases (25%) inhibition was not successful and explained by a warm-reactive autoantibody plus anti-E (n=1), nonspecific reactivity (n=1) and reactions to a high-prevalence antigen not related to the rBGAs used (n=1). Specificities of rBGAs and antibodies are detailed in Table 1.

Conclusion

Hemagglutination inhibition assays using rBGAs can easily be carried out in a routine testing laboratory without the need of rare test cells or antisera, or sometimes complicated and time-consuming procedures. In 75% of our cases the antibody specificity to a high-prevalence antigen were determined and all additionally identified single or multiple alloantibodies were clinically significant. Recombinant blood group antigens are a valuable tool to increase transfusion safety.

Offenlegung Interessenkonflikt:

AS is a member of the scientific advisory board of Imusyn (manufacturer of the rBGAs). All other authors: None