Novel method of blood typing by cell capillary electrophoresis under microscopic observation

Agglutinations with cross reactions between red blood cells and blood-tying antibodies in a short fused-silica capillary tubing (50 μm inner diameter and ca. 10 mm in length) were observed by an optical microscope-CCD camera system. The total volume in the capillary was only about 20 nl. The cross reaction was induced by using of counter electrophoretic migrations between red blood cells and the antibody under an applied electric voltage. Since the microscopic magnification was 1000 times, each red blood cell could be clearly observed. The blood typing procedure was as follows: after 50-times diluted whole blood cells were introduced into a capillary, both ends of the capillary were sealed with 1% agarose gels in order to suppress any pressurized flow in the capillary. Then, a direct electric voltage was applied (24 V) to the capillary. The red blood cells migrate toward the positive electrode against electroosmotic flow, while the blood plasma migrated toward to the negative electrode. The blood antibody in the reservoir of the positive electrode was introduced through the stopper of the agarose gel, following a cross-reaction with the red blood cells. Agglutination of some of the red blood cells was observed with a CCD camera and recorded on video-tape. The operation period took only 5 min. This new blood typing was performed using whole blood of nl volume.