Red blood cell aggregation, aggregate strength and oxygen transport potential of blood are abnormal in both homozygous sickle cell anemia and sickle-hemoglobin C disease.
BACKGROUND
Recent evidence suggests that red blood cell aggregation and the ratio of hematocrit to blood viscosity (HVR), an index of the oxygen transport potential of blood, might considerably modulate blood flow dynamics in the microcirculation. It thus seems likely that these factors could play a role in sickle cell disease.


METHODS
We compared red blood cell aggregation characteristics, blood viscosity and HVR at different shear rates between sickle cell anemia and sickle cell hemoglobin C disease (SCC) patients, sickle cell trait carriers (AS) and control individuals (AA).


RESULTS
Blood viscosity determined at high shear rate was lower in sickle cell anemia (n=21) than in AA (n=52), AS (n=33) or SCC (n=21), and was markedly increased in both SCC and AS. Despite differences in blood viscosity, both sickle cell anemia and SCC had similar low HVR values compared to both AA and AS. Sickle cell anemia (n=21) and SCC (n=19) subjects had a lower red blood cell aggregation index and longer time for red blood cell aggregates formation than AA (n=16) and AS (n=15), and a 2 to 3 fold greater shear rate required to disperse red blood cell aggregates.


CONCLUSIONS
The low HVR levels found in sickle cell anemia and SCC indicates a comparable low oxygen transport potential of blood in both genotypes. Red blood cell aggregation properties are likely to be involved in the pathophysiology of sickle cell disease: the increased shear forces needed to disperse red blood cell aggregates may disturb blood flow, especially at the microcirculatory level, since red blood cell are only able to pass through narrow capillaries as single cells rather than as aggregates.
Tripette
Julien
J
Laboratoire ACTES, EA 3596, Département de Physiologie, Université des Antilles et de la Guyane, Campus de Fouillole, Pointe-à-Pitre, Guadeloupe, French West Indies.
Alexy
Tamas
T
Hardy-Dessources
Marie-Dominique
MD
Mougenel
Daniele
D
Beltan
Eric
E
Chalabi
Tawfik
T
Chout
Roger
R
Etienne-Julan
Maryse
M
Hue
Olivier
O
Meiselman
Herbert J
HJ
Connes
Philippe
P
D000755:Anemia, Sickle Cell / Q000097:blood* / Q000235:genetics; D001692:Biological Transport; D001809:Blood Viscosity; D004903:Erythrocyte Aggregation; D004907:Erythrocyte Deformability; D004912:Erythrocytes / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism; D006400:Hematocrit; D006444:Hemoglobin C / Q000378:metabolism; D006445:Hemoglobin C Disease / Q000097:blood* / Q000235:genetics; D006451:Hemoglobin, Sickle / Q000378:metabolism; D018056:Hemorheology; D006720:Homozygote; D006801:Humans; D010100:Oxygen / Q000378:metabolism*
D006451:Hemoglobin, Sickle; D005340:Fibrinogen; D006444:Hemoglobin C; D010100:Oxygen