The hemolysis kinetics of psoriatic red blood cells

Psoriasis has been reported to be associated with several red blood cell (RBC) membrane alterations including: a membrane fluidity decrease, a significant elevation of Na(+)-K(+)and quantitative changes of erythrocyte membrane proteins that may indicate red cell cytoskeleton impairment. The aim of the present study was to analyse the hemolytic behaviour of psoriatic RBCs. The osmotic behaviour of RBCs was examined by analysing the kinetics of hemolysis. The method is based on the measurement of the transmitted light (lambda=700 nm) scattered by a suspension of red blood cells subjected to osmotic stress in the stopped-flow regime. The transmittance as a function of time, which describes the lysis kinetics, can be satisfactorily fitted with a mathematical model which assumes three cell populations in each sample: cells that do not lyse in the experimental conditions and cells that undergo fast and slow lysis. A comparison of the erythrocyte hemolytic kinetics of blood samples from psoriatic patients and healthy subjects showed distinct differences. The fraction of hemolyzed erythrocytes for control samples was about 20%; for psoriatic ones 12.6% (P<0.001). In control blood samples the fraction of fast-breaking cells was greater (about 61% of lysed cells) than in psoriatic ones (about 56%). The parameter T(fast), describing the time of fast kinetics and T(slow), which reflects the rupturing time of cells belonging to the fraction of slow hemolysing cells were significantly higher for psoriatic erythrocytes than for control cells (P<0.001). It was shown that the psoriatic erythrocyte has a low propensity for hemolysis and that its plasma membrane is distinctly more resistant to osmotic stress, probably related to decreased bilayer fluidity and low cell deformability. The results of this study showed that the kinetics of hemolysis may be a promising method for detecting erythrocytes with defective plasma membrane components and/or defective cytoskeleton organization and indirectly can provide some information on cell function.