Ultraviolet and visible light spectrophotometric approach to blood typing:objective analysis by agglutination index

BACKGROUND: A new blood typing technology based on ultraviolet (UV) and vis ible light spectroscopy (UV/visible spectroscopy) has been developed. Blood groups and types are determined by quantifying reproducible changes in the UV and visible light spectra of blood in the presence of agglutinating ant ibodies. STUDY DESIGN AND METHODS: Samples of red cells in the presence and absence of agglutinating antibodies were examined by UV/visible spectroscopy. Blood groups and types were determined by comparing the optical density spectra obtained between 665 and 1000 nm. These comparisons generate numbers (agglu tination index) ranging from 0 to 100, with smaller numbers corresponding t o lack of agglutination and larger numbers corresponding to agglutination. RESULTS: The optical density of agglutinated blood is dramatically differen t from that of unagglutinated blood. The agglutination index derived from t he relative slopes of the spectra is an objective indicator of agglutinatio n strength. An agglutination index greater than 17 consistently and accurat ely established blood group- and type-specific agglutination. CONCLUSION: The method accurately predicted A, El, and O blood groups, and D type in over 275 samples. Scattering theory-based calculations of relativ e volumes of red cells before and after agglutination show a direct correla tion with the agglutination index and provide the theoretical basis of the analysis. This quantitative technique is reproducible and has the potential for automation.