Abstract: Objective To explore the effects of carbohydrates and metal ion chelators present in common red blood cell (RBC) preservatives on the agglutination intensity of serological reactions between Dolichos Biflorus Agglutinin (DBA) and A₁ RBCs, thus provide evidence for minimizing false negative results in clinical testing and enhancing the understanding of DBA's functional characteristics. Additionally, our study attempted to propose improvements to the current laboratory quality control procedures for A₁ antigen identification. Methods The agglutination intensity of DBA-A₁ erythrocytes under various conditions was quantitatively measured. This was achieved by introducing serial dilutions of sugar solutions (glucose, sucrose, mannitol) and performing checkerboard titrations of EDTA-Na₂ and divalent metal cations (Ca²⁺, Mg²⁺) into the reaction system. Throughout the experiments, 0.9% saline was used as the initial RBC diluent. Results C_EDTA-Na2 concentrations >0.6 mM significantly inhibited agglutination, while increasing concentrations of Ca²⁺/Mg²⁺ reduced the negative effect of high concentration EDTA-Na₂. On the other hand, a notable decrease in DBA-A₁ erythrocyte agglutination intensity was observed with increasing sugar concentrations. Specifically, the addition of 0.6% to 5% glucose solution, 1.3% to 10% sucrose solution or 5% mannitol solution significantly weakened the aggregation of DBA-A₁ red blood cells. Conclusion EDTA-Na₂ and saccharides in RBC preservatives could exhibit inhibitory effects on the agglutination reaction between DBA and A₁ RBCs, highlighting them as crucial risk factors in the application of plant lectins for blood group serological detection.

Key words: Dolichos Biflorus Agglutinin, Reagent red blood cells, Red blood cell preservation additive, A₁ subtype