Mechanical properties of sickle cell membranes
R Messmann, S Gannon, S Sarnaik and RM Johnson
Department of Biochemistry, Wayne State Medical School, Detroit, MI 48201.
The mechanical properties of sickle erythrocyte membranes were evaluated in
the ektacytometer. When ghosts from the total red blood cell population
were examined, the rigidity of the resealed ghosts and their rate of
fragmentation by shear stress (t1/2) were normal. However, fractionation on
Stractan density gradients revealed that sickle cells were heterogenous in
their membrane mechanical properties. The ghosts from dense cell fractions
exhibited both increased rigidity and decreased stability. Presumably,
these altered mechanical properties are a reflection of the well-documented
biochemical damage found in irreversibly sickle cell membranes.
Nevertheless, neither of the alterations in mechanical properties are
likely to be significant elements in the hemolysis of sickle cell anemia.
Earlier studies of abnormal erythrocytes suggest that increases in membrane
rigidity per se do not increase hemolysis, and they are, therefore,
unlikely to do so in this case. The stability of membranes from the dense
cell fractions was reduced to about two thirds of the control value.
Comparison with the results of studies of red blood cell membranes with
genetically defective or deficient spectrin suggests that a reduction in t
1/2 of 50% is not associated with significant increases in the rate of
hemolysis. Although altered ghost stability and flexibility can be
demonstrated in dense sickle cells, these changes in membrane mechanical
properties are not likely to be significant factors in the hemolytic
process.
Volume 75,
Issue 8,
pp. 1711-1717,
04/15/1990
Copyright © 1990 by The American Society of Hematology
