Duffy blood group (Fy^a & Fy^b) analysis using surface plasmon resonance

The most widely known blood groups, ABO and RhD, have been extensively observed as having strong antibody-antigen interactions during blood typing. However, not all interactions show the same binding affinity. The Duffy blood group system, where Fy^a and Fy^b antigens are the most clinically significant, are only available with an IgG antibody structure, and display weak binding interactions. While current blood typing techniques are well established, methods for quantifying the binding strength are more limited. Surface Plasmon Resonance (SPR) provides avenues for developing more robust detection methods, and serve as a sensitive quantification technique by itself. This study tested SPR for the detection of weaker antibody-antigen interactions using the Duffy blood groups, Fy^a and Fy^b, as a model. This study shows a minimum threshold of antibody concentration is required for successful detection. Some instances of detection were successful using concentrated commercial anti-Fy^a and anti-Fy^b solution during the incubation stage. However, these results were not fully reproducible. We found that a significant dissociation of the Duffy antigen-antibody complex occurs over time. A combination of factors affects the detection of the Duffy antigens using SPR; these include antibody concentration, antigen expression, and antigen structure. This results in weak, unstable and reversible antibody-antigen interactions which are currently limiting accurate and reproducible detection by SPR. Despite these issues, detection of Duffy antigens Fy^a and Fy^b was demonstrated using SPR; however, further development is required for SPR to become a robust clinical blood typing technique.