Basic principles for evaluation of less deformable erythrocyte subpopulations with the Microfiltrometer.
The Microfiltrometer consists of a filtration system for diluted erythrocyte suspensions, through a filter containing 30 cylindrical micropores, 5 microm in diameter, under the influence of a driving pressure. A feeding sinusoidal alternating current of 40 kHz, 300 microA is delivered to the filter. The change in impedance is collected for each temporary flow of erythrocytes through a given micropore. Two main parameters are measured for individually explored erythrocytes: the entry time tau in the micropore and the maximal variation of impedance deltaZ occurring for the transitory flow. The slope deltaZ/tau defines the velocity of pore blockage. A "Microfiltrometer Deformability Index" (MDI) is established by using this slope. When MDI > or = 1, the erythrocyte is considered to be deformable and, conversely, when MDI < 1, the erythrocyte is considered to be undeformable. Using this procedure, less than 2% undeformable erythrocytes in healthy blood samples are identified, with a specificity of 99% and a sensitivity of 97.5%.
Amoussou-Guenou
K M
KM
UER de Biophysique, University d'Abomey-Calavi, Faculté Sciences de la Santé, Bénin.
Martinsen
O G
OG
Hounkponou
M
M
Doumit
J
J
Healy
J C
JC
D048430:Cell Shape / Q000502:physiology; D003584:Cytological Techniques / Q000379:methods*; D017097:Electric Impedance; D004907:Erythrocyte Deformability / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology; D005374:Filtration / Q000295:instrumentation; D006358:Hot Temperature; D006801:Humans; D008851:Micropore Filters; D011312:Pressure; D015203:Reproducibility of Results