The duffy blood group system is functionally associated with:

# The duffy blood group system is functionally associated with:

a. Invasion by P. falciparum

b. Red cell urea transporter

c. Maintenance of membrane integrity

d. Invasion by P. vivax

The correct answer is: D. Invasion by P. vivax.

Duffy antigen is a receptor for Plasmodium vivax.

• The receptor for P. falciparum on RBCs are glycophorins

• Red cell urea transporter is the Kidd antigen and its absence can be associated with impaired urea transport and urine concentrating defect.

• Integral membrane proteins are band 3, glycophorins, Rh, Kell,  Kidd, Duffy and Lutheran glycoproteins. Though Duffy is an integral membrane protein but it is not the major protein involved in the overall integrity of RBC membrane.

• The peripheral membrane proteins are spectrin, ankyrin, actin, protein 4.1, 4.2 and 4.9, p 55 and the adducins.

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Howell–Jolly bodies contain

 # Howell–Jolly bodies contain: 

a. Iron 

b. DNA 

c. RNA 

d. Protein

The correct answer is B. DNA.

A Howell–Jolly body is a cytopathological finding of basophilic nuclear remnants (clusters of DNA) in circulating erythrocytes. During maturation in the bone marrow, late erythroblasts normally expel their nuclei; but, in some cases, a small portion of DNA remains.

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Pappenheimer bodies contain:

 # Pappenheimer bodies contain: 

a. Iron 

b. DNA 

c. RNA 

d. Ribosomal proteins

The correct answer is a. Iron.

Pappenheimer bodies are abnormal basophilic granules of iron found inside red blood cells on routine blood stain. They are a type of inclusion body composed of ferritin aggregates, or mitochondria or phagosomes containing aggregated ferritin.

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Membrane rigidity and fragility can be measured by:

 # Membrane rigidity and fragility can be measured by:

a. Osmocytometer

b. Spherocytometer

c. Ektacytometer

d. Viscometer

The correct answer is C. Ektacytometer. 

Osmotic gradient ektacytometry measures RBC deformability under a defined shear stress as a function of suspending medium osmolality. The test is used to evaluate for inherited RBC membrane disorders, which are commonly responsible for hemolytic anemia, differentiating among hereditary spherocytosis (HS), hereditary elliptocytosis (HE) and pyropoikilocytosis (HPP), Southeast Asian ovalocytosis (SAO) and hereditary stomatocytosis (HSt).

Osmotic Gradient Ektacytometry at Cincinnati Children's.Ektacytometry is recommended as the next step after hemoglobin electrophoresis in the diagnosis of a non-immune hemolytic anemia. An abnormal ektacytometry profile confirms a red cell membrane disorder and assists with the differential diagnosis between hereditary spherocytosis versus elliptocytosis / pyropoikilocytosis versus xerocytosis. This is particularly important in xerocytosis where splenectomy is contraindicated because it precipitously increases the risk for life-threatening thrombophilia. Ektacytometry in a patient with a non-transfusion dependent hemolytic anemia may save the need to perform a hereditary hemolytic anemia genetic panel. It can also help focus the genetic workup to a red cell membrane panel if ektacytometry is positive or to a red cell enzyme panel if ektacytometry is negative.

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