LASER-ASSISTED OPTICAL ROTATIONAL CELL ANALYZER (LORCA) .2. RED-BLOOD-CELL DEFORMABILITY - ELONGATION INDEX VERSUS CELL TRANSIT-TIME

Red blood cell deformability was measured under normal and experimenta l conditions with the Laser-assisted Optical Rotational Cell Analyser (LORCA). Results were compared to simultaneously performed filtration measurements using the Cell Transit Analyser (CTA). The deformability parameters of the two methods were Elongation Index (EI) and mean Cell Transit Time (CTT, respectively. Aside from instrumental and intra-in dividual reproducibility, normal values, the effect of sample aging an d of changing medium osmolality are reported. Furthermore, the respect ive sensitivities were determined using red blood cells with slightly impaired deformability. Both heat treatment and incubation in the pres ence of low concentrations of glutaraldehyde are used to manipulate th e deformability of the entire red cell population. It is concluded tha t minor defects in red blood cell deformability are detected more easi ly by the laser technique than by filtration. Even when the absolute d ifferences in EI are small, they can be significant due to the very hi gh reproducibility of the ektacytometric technique. Differentiation be tween a decreased deformability of the entire RBC population and the p resence of a small (i.e., 5% or higher) subpopulation of rigid cells c an be achieved with the LORCA by combining the measured EI-values with visual inspection of the diffraction pattern. Finally, no significant correlation was found between the results of both techniques applied to blood from 525 patients with various diseases.