[Quantitation of hemagglutinins using new microtitration plate (R-plate) and ELISA reader].

A new type of microtitration plate (reverse-shaped bottom plate, R-plate) was used in quantitative hemagglutination test. The bottom of the well of this plate was shaped convex and the hemagglutination patterns were measured as photometric value by the ELISA reader. Agglutinated erythrocytes adhered to the convex bottom of the well and were detected as large absorbance. Non-agglutinated erythrocytes gather in the circle of the peripheral edge with clear center area. As shown in the detection limits of anti-A and anti-B hemagglutinins, sensitivity of the R-plate hemagglutination method was 4 times superior to those of conventional hollowed glass-slide technique. Reproducibility (C.V.) of the R-plate hemagglutination method was between 1 and 3%. The R-plate agglutination method described here is easy to assay and thought to provide a potentially useful method for medical research and clinical laboratory tests.