Indirect antiglobulin paper test for red blood cell antigen typing by flow-through method

This study reports a rapid and user friendly paper blood typing assay based on the Indirect Antiglobulin Test (IAT) principle. Red blood cells (RBCs) were incubated with IgG anti-D and supernatant was removed post-incubation. The remaining RBCs were spotted on paper pre-treated with anti-IgG. A few drops of washing saline solution were deposited onto the blood spot on paper to flow through all non-agglutinated RBCs, leaving a clear white paper; this indicates a negative sample. Agglutinated RBCs resist saline solution flushing and form a bright red spot on paper signalling a positive reaction to the antibody tested. The IAT on paper successfully identified RBCs sensitised by IgG anti-D. Positive samples were clearly distinguished from negative samples. The critical variables were optimised to maximise the sensitivity and reproducibility of the paper diagnostic. This paper-based IAT assay further simplifies the current methods for IgG antibody-based RBC antigen typing. Its rapid and easy-to-read characteristics enable automated high-throughput analytical systems or a simple manual test for operators with minimum skills required.