Sickle cells These photos show sickle cells on peripheral blood smears. In the left photo target cells are also seen, in the right photo, target cells and spherocytes; the patient represented by the right photo had b–thalassemia in addition to sickle cell disease. The tendency to sickle is closely correlated with the concentration of HbS in the cell. Heterozygous HbS (sickle cell trait) individuals have about 40% HbS, the rest being normal HbA which is protective against HbS aggregation and polymerization. Persons with trait do very well clinically and have no significant anemia. Their erythrocytes do not sickle unless they are exposed to severe hypoxia, e.g. there were reports of airmen with sickle cell trait in the mid-20th century developing sickle cell nephropathy when flying at high altitudes without proper cabin compression. The presence of other hemoglobins also alters the propensity for sickling of cells containing HbS. Examples of dampening of the sickling phenomenon include the normal presence of HbF during the first few months of life, the abnormal persistent elevation of HbF in some persons such as patient with thalassemia, and HbSC disease. #Clinical #Path #BloodSmear #Blood #Smear #SickleCells #Sickle #SickleCellAnemia
