It has been hypothesized that the well-known decreased deformability of oxygenated sickle (HbSS) RBCs could result from auto-oxidative perturbation. Density separated RBCs from steady-state HbSS subjects and normal HbAA donors were incubated in PBS/glucose for 60 min. with 0, 100 and 1000 micromol phenazine methosulpate (PMS). To examine the effects of oxidative stress, we used a micropore filtration system to measure deformability of density separated RBC subpopulations. The Cell Transit Analyser (CTA) provides a means to rapidly measure the deformability of large numbers of individual cells. For the same RBC samples, the superoxide-dependent reduction of horse ferricytochrom c was also detacted. Salient findings were: 1) significantly decreased deformability of SS RBC; 2) higher spontaneous superoxide radical generation by sickle erythrocytes; 3) significantly greater superoxide production for SS RBC at both PMS concentrations; 4) denser cells are more rigid and produce more superoxide radicals.

Our results indicate that SS cells are more sensitive than AA cells to oxidative stress and that subpopulations respond differently; they support the concept that oxidative mechanisms play an important role not only in abnormal rheology of SS RBC but in cell aging as well.