The Sedimentation Rate of Free Erythrocytes and Their Associates, the Influence of a Standing Ultrasonic Wave

A comparative analysis of the sedimentation rates of free erythrocytes and their associates – aggregates and agglutinates was carried out. The influence of a standing ultrasonic (US) wave on the blood sedimentation process was investigated. The problem was dictated not only by a purely scientific interest in the sedimentation of micro–objects in a liquid medium, but from a practical point of view also – the development of an instrumental acousto–optical method for human blood group typing. Registration of the blood sedimentation process was carried out by means of digital video recording with subsequent computer processing of the photographic images obtained. The magnitude of blood sedimentation rate was experimentally determined for various samples and conditions: 1) blood solutions with / without ultrasound exposure for different time dosages; 2) a mixture of blood samples with hemagglutinating substances (Tsoliklon) without / with ultrasonic action both for a positive agglutination reaction (formation of agglutinates) and negative ones (absence of agglutinates). Two approaches were used to process the photographic images: 1) in the case of agglutinates sedimentation the discrete counting and analysis of agglutinate parameters were used; 2) in other cases, the blood sedimentation rate was determined by the movement of the "supernatant – sediment" (plasma solution – erythrocytes mass) boundary. For the experimental conditions accepted the blood sedimentation rates were compared and, correspondently, the influence of the ultrasonic standing wave upon the process under study was estimated. It was shown that in the presence of ultrasound the sedimentation rate of RBC agglutinates (positive agglutination reaction) is more than an order higher than the sedimentation rate of free erythrocytes and their aggregates (negative agglutination reaction). Such a great difference in the sedimentation rates of agglutinates in comparison with free erythrocytes and their aggregates makes it possible to obtain a high degree of resolution of acousto–optical method for instrumental blood typing, and, hence, high reliability in blood group determination.