Filterability of sickle cells as a function of pO 2 : Role of physico-chemical factors

Abstract

A rigidity index (RI) related to red blood cell deformability was measured by using the hemorheometre. The RI for 13 patients homozygous for sickle cell disease was 109 ± 44 at 37°C and at atmospheric pO₂. The filtration time curve as a function of pO₂ is biphasic for sickle cell suspensions. The pO₂ at which filtration time is maximum, pO₂ ^max., correlated with the rigidity index measured at atmospheric pO₂. This pO₂ ^max. value was very sensitive to small changes in physico-chemical parameters such as osmolality, pH, temperature, hematocrit, and cell density. Conditions which reduced the Hb S polymerization induced a leftward shift of pO₂ ^max.. The experimental curves are in agreement with theoretical models based on the presence of two abnormal cell types: filtrable “slow cells” and infiltrable “sickled cells“.