Quantitative Detection of Weak D Antigen Variants in Blood Typing using SPR

Area of Science:

• Immunology
• Biotechnology
• Hematology

Background:

• Quantifying blood group antibody-antigen interactions is challenging, particularly for weak or partial antigen expressions.
• Current methods for detecting weaker blood group variants are often subjective and lack precision.
• Surface Plasmon Resonance (SPR) is a sensitive technique for monitoring biomolecular interactions.

Purpose of the Study:

• To evaluate the sensitivity of a regenerable SPR platform for detecting weak D and partial D blood group variants.
• To establish a quantitative and objective method for analyzing weaker blood group antigen expressions.
• To demonstrate the capability of SPR in differentiating between normal, weak, and partial D antigen expressions.

Main Methods:

• Utilized a regenerable SPR platform with immobilized anti-human IgG antibodies on a gold sensor surface.
• Tested the platform with pre-sensitized red blood cells (RBCs) exhibiting weak D and partial D variants.
• Quantified binding using response units (RU), with >100 RU indicating positive binding and <100 RU indicating negative binding.

Main Results:

• Successfully detected weak D variants within a range of 180-580 RU, reflecting lower antigen expression.
• Identified partial D variants (category D VI) within a range of 352-1147 RU, comparable to normal D antigen detection.
• Demonstrated the platform's ability to differentiate and quantify two classes of weaker D variants.

Conclusions:

• The regenerable SPR platform effectively quantifies weak D and partial D blood group variants for the first time.
• This SPR-based approach provides a sensitive, objective, and reproducible alternative to current subjective methods.
• The findings open new avenues for improved blood group phenotyping and transfusion safety.