Universal Assay Platform Allows Rapid Blood Grouping

A new study describes how a paper-based point-of-care assay could provide fast and reliable blood group testing at the patient’s bedside.

Developed by researchers at Third Military Medical University, the paper-based assay uses immobilized antibodies and bromocresol green dye for rapid and reliable blood grouping, where dye-assisted color changes corresponding to distinct blood components provide a visual readout for each antigen (A, B, and Rhesus). The researchers also developed a machine-learning method that can classify spectral plots corresponding to the color changes, which enables reproducible automatic grouping.

The assay identifies ABO antigens and five major Rhesus antigens within 30 seconds using small volumes (100 μl) of whole blood, thus allowing simultaneous forward and reverse ABO blood grouping within two minutes through on-chip plasma separation, and all without centrifugation. When tested with optimized operating parameters, the dye-assisted paper assay exhibited comparable accuracy and reproducibility to the classical gel-card assays in grouping 3,550 human blood samples, with more than 99.9% accuracy. The study was published on March 15, 2017, in Science Translational Medicine.

“Fast and simultaneous forward and reverse blood grouping has long remained elusive. Forward blood grouping detects antigens on red blood cells, whereas reverse grouping identifies specific antibodies present in plasma,” concluded lead author Hong Zhang, PhD, and colleagues. “The paper strip could be used in war zones or remote areas where there are no labs to test patients’ blood types. O blood is currently used in these contexts, but supplies are limited.”

There are four major blood groups determined by the presence or absence of two antigens (A and B) on the surface of red blood cells (RBCs). Group A has only the A antigen on RBCs, and B antibody in the plasma; Group B has only the B antigen on RBCs, and A antibody in the plasma; Group AB has both A and B antigens on RBCs, but neither A nor B antibody in the plasma; and Group O has neither A nor B antigens on RBCs, but both A and B antibody in the plasma. In addition to the A and B antigens, there is a third antigen called the rhesus (Rh) factor, which can be either present (+) or absent (–). The universal red cell donor has Type O– blood type, and the universal plasma donor has Type AB+ blood type.