13. Hemolytic Anemias: Extracorpuscular Defects

Question 1

1. What are the mechanisms of immune hemolysis?

a. IgG or IgM antibodies that activate the classical com-plement pathway
b. Antibody-dependent cellular cytotoxicity (ADCC)mediated by NK cells, monocytes/macrophages,and granulocytes
c. Complete or partial phagocytosis of antibody-coated erythrocytes
d.All of the above

Answer 1

d.All of the above

Question 2

2. Which would best distinguish hemolytic anemia caused by immune mechanisms from other hemolytic anemias?
   a. Presence of spherocytes on peripheral blood film
   b. Increased reticulocyte count
   c.Enlarged spleen
   d.Positive DAT

Answer 2

d.Positive DAT

Question 3

3.Which is true concerning autoimmune hemolytic anemia?

a. Majority of cases are ofthe“cold”type
b. Seen in transfusion reactions
c. Is demonstrated in hemolytic disease of the newborn
d. Antibodies are produced against one’s own erythro-cyte antigens

Answer 3

d. Antibodies are produced against one’s own erythro-cyte antigens

Question 4

4.What is the process in which the immune system pro-duces antibodies to foreign red cell antigens introduced into their circulation through transfusion, pregnancy, or organ transplantation?
a. Alloimmune hemolytic anemia
b.Autoimmune hemolytic anemia
c. Drug-induced immune hemolytic anemia
d.None of the above

Answer 4

a. Alloimmune hemolytic anemia

Question 5

5. What causes hemolytic disease of the newborn(HDN)?
   a. Maternal IgG antibodies, formed as a result of a previ-ous blood exposure or pregnancy, cross the placenta and attach to fetal cells.
   b. Fetal IgG antibodies cross the placenta and attach to maternal red cells.
   c.Maternal IgMantibodies, formed as a result of a pre-vious blood exposure or pregnancy, cross the placenta and attach to fetal cells.
   d. Fetal IgM antibodies attach to fetal red cells and cross the placenta to enter the mother’s circulation.

Answer 5

a. Maternal IgG antibodies, formed as a result of a previ-ous blood exposure or pregnancy, cross the placenta and attach to fetal cells.

Question 6

6.Which is not a characteristic of warm autoimmune hemolytic anemia?
a. Variable anemia
b.Reticulocytosis and spherocytosis
c.Positive result for Donath-Landsteiner test
d.DAT result usually positive for both lgG and C3d

Answer 6

c.Positive result for Donath-Landsteiner test

Question 7

7.What are features of cold agglutinin syndrome?
a.Usually an IgM antibody
b.Reticulocytosis and positive DAT
c.Tendency for spontaneous autoagglutination of RBC samples
d.All of the above

Answer 7

d.All of the above

Question 8

8.What is the principle of the Donath-Landsteiner test?
a.Antibody binds red cells at 37℃ and causes lysis at 4℃.
b. Antibody binds red cells at 4°C and causes lysis at 37℃.
c. Antibody binds red cells at 4℃ or 37℃ and causes immediate lysis.
d. Antibody binds red cells at 4℃ o 37℃ but causes lysis only at 4℃.

Answer 8

b. Antibody binds red cells at 4°C and causes lysis at 37℃.

Question 9

9.What are causes for nonimmune hemolytic anemia?
a.Infections
b.Mechanical,chemical,and physical agents
c. Acquired membrane disorders
d.All of the above

Answer 9

d.All of the above

Question 10

10.Which of the following organisms is (are) associated with hemolytic anemia?
a. Mycoplasma pneumoniae
b. Clostridium perfringens
c.Babesia microti
d.All of the above

Answer 10

d.All of the above

Question 11

11.Which of the following, as measured via an automated hematology instrument,would most likely be affected by a cold agglutinin?
a.Hemoglobin
b.Hematocrit
c.Platelet count
d.Leukocyte count

Answer 11

b.Hematocrit

Question 12

12.Which of the following drugs causes a hemolytic anemia resulting from production of “true autoantibodies” rather than antibodies to the drug or to the drug-erythrocyte complex?

a.Penicillin
b.Cephalosporin
c.Aldomet
d. Quinidine

Answer 12

c.Aldomet