Deck 21: Autoimmune Hemolytic Anemias

Question 1

In the case of an AB-positive individual, what test must be performed to ensure that a warm-reacting autoantibody is not causing false-positive reactions?

A) Rh control
B) DAT
C) IAT
D) Rosette test

Answer 1

A

Question 2

Which of the following factors distinguishes a cold autoantibody produced in a patient with infectious mononucleosis from that produced in a patient with pneumonia?

A) A titer greater than 64
B) An IgM class of antibody
C) A wide thermal range
D) Anti-i specificity

Answer 2

D

Question 3

Most cases of warm autoimmune hemolytic anemia will be DAT-positive with which of the following?

A) Anti-IgG only
B) Anti-C3d only
C) Both anti-IgG and Anti-C3d
D) None of the above

Answer 3

C

Question 4

Cold hemagglutinin disease represents what percentage of autoimmune hemolytic anemia (AIHA) cases?

A) 18
B) 70
C) 12
D) 25

Question 5

Which of the following procedures can be used to resolve interference due to anti-I?

A) Cold autoadsorption
B) Prewarm technique
C) Warm adsorption
D) Cold autoadsorption and prewarm technique

Question 6

All of the following are clinical manifestations of cold hemagglutinin disease (CHD) except:

A) agglutination of red blood cells in skin capillaries.
B) acrocyanosis of the hands and feet.
C) hepatosplenomegaly.
D) Raynaud's phenomena.

Question 7

Which of the following is a proposed theory for methyldopa-induced mechanism of immune hemolytic anemia?

A) Normal red blood cell antigens are altered by the drug and are no longer recognized as "self," resulting in production of alloantibody to these red blood cell antigens.
B) The drug affects the synthesis of IgG, exerting a direct effect on T lymphocytes, which results in a loss of suppressor function and subsequent proliferation of autoantibodies by B lymphocytes.
C) The drug produces aberrations in the proliferation of normal lymphocytes, producing clones of normal immunologically competent cells, which produces antibody against foreign red blood cell antigens.
D) The drug modifies the red blood cells so that plasma proteins bind to the membrane.

Question 8

The onset of warm autoimmune hemolytic anemia (WAIHA) may be precipitated by:

A) pregnancy.
B) bacterial infection.
C) trauma.
D) all of the above.

Question 9

In warm autoimmune hemolytic anemia, the autoantibody will frequently demonstrate -like specificity.

A) Fy^a
B) K
C) Rh
D) Jk^b

Question 10

RBCs sensitized in which drug-induced hemolytic anemia mechanism act as "innocent bystanders"?

A) Membrane modification
B) Immune complex
C) Drug absorption
D) Autoantibody formation

Question 11

How might a technologist detect a patient with drug-induced hemolytic anemia?

A) Positive rosette test
B) Positive antibody screen
C) Positive DAT
D) ABO discrepancy

Question 12

Which drug can cause production of autoantibody?

A) Ibuprofen
B) Isoniazid
C) Methyldopa
D) Tetracycline

Question 13

A patient with a positive DAT needs to be phenotyped for Jk^a. What reagent can be used on red blood cells to ensure accurate typing?

A) DTT
B) Chloroquine diphosphate
C) Ficin
D) Digitonin

Question 14

Which of the following characterizes an alloimmune response in immune hemolytic anemia?

A) The patient produces an antibody reactive with her own red blood cells.
B) The patient produces an antibody to a prescribed antibiotic.
C) The patient produces anti-K to transfused red blood cells.
D) None of the above

Question 15

Which of the following can be found in warm autoimmune hemolytic anemia in the presence of hypoplastic marrow?

A) Reticulocytopenia
B) Polychromasia
C) Reticulocytosis
D) Thrombocytopenia

Question 16

In the digitonin-acid elution procedure, what is the purpose of adding phosphate buffer to the eluate solution?

A) To disperse any debris left in the eluate
B) To protect against hemolysis
C) To restore neutrality to the eluate
D) To elute antibody from red blood cell membrane

Question 17

Cold autoanti-H is more prevalent in which blood group?

A) A₂
B) O
C) A₁B
D) B

Question 18

How can persons with CHD avoid hemolytic episodes?

A) Have a splenectomy
B) Move to a warm climate
C) Corticosteroid therapy
D) None of the above

Question 19

In which of the following is the DAT reactive with anti-C3d only?

A) Drug adsorption mechanism
B) Warm autoimmune hemolytic anemia
C) Cold hemagglutinin disease
D) Membrane modification

Question 20

If a false-positive reaction was suspected with anti-D in the forward grouping due to the presence of a cold autoantibody, which of the following would show reactivity?

A) Du test
B) DAT
C) Rh control
D) All of the above

Question 21

How is RBC destruction characterized in drug-induced immune hemolytic anemia via immune complex mechanism?

A) Extravascular hemolysis via macrophage ingestion of drug complex
B) Red blood cell death due to toxic granules released by neutrophils
C) Intravascular hemolysis precipitated by complement activation
D) None of the above

Question 22

What percentage of AIHA cases are caused by warm reacting autoantibodies?

A) 18%
B) 70%
C) 12%
D) 25%

Question 23

What technique can be used to identify an alloantibody in the presence of a cold autoagglutinin?

A) Prewarming
B) Enzyme treatment
C) Chloroquine treatment
D) Polyethylene glycol

Question 24

Which of the following describes the drug-adsorption (hapten) mechanism?

A) Drugs bind firmly to proteins of the RBC membrane.
B) A soluble drug-antidrug complex absorbs nonspecifically to red blood cell membrane.
C) Drugs alter the red blood cell membrane so that plasma proteins then bind to the membrane.
D) The drug induces production of an autoantibody that recognizes red blood cell antigens.

Question 25

In a patient who has been recently transfused, a positive DAT may be due to:

A) alloantibody coating patient cells.
B) alloantibody coating transfused donor cells.
C) antibodies to a drug coating donor cells.
D) none of the above.

Question 26

What is the primary goal for treatment in patients with warm autoimmune hemolytic anemia?

A) Reduce neoplastic tumors
B) Treat coexisting anemia
C) Treat the underlying disease
D) None of the above

Question 27

Why do clotted specimens yield positive DAT results with anti-C3 in the presence of a benign cold autoagglutinin?

A) Complement is inhibited due to calcium chelation.
B) Complement can be activated in vivo.
C) Complement can be activated in vitro.
D) Complement is activated in the absence of fibrinogen.

Question 28

Which alloantibody is frequently present in the serum of i adults?

A) Anti-IH
B) Anti-H
C) Anti-I
D) All of the above

Question 29

What is the most common drug associated with the drug-adsorption mechanism?

A) Erythromycin
B) Penicillin
C) Methyldopa
D) Insulin

Question 30

Approximately what percentage of AIHA cases are due to paroxysmal cold hemoglobinuria (PCH)?

A) 70%
B) 12%
C) 1% to 2%
D) 18%

Question 31

How is the serology workup for an autoantibody produced by a drug-induced hemolytic anemia different from other autoantibody workups?

A) The antibody will only be reactive with red blood cells in the presence of the drug.
B) The antibody is not detected in the presence of the drug.
C) Eluate is detectable when drug-coated red blood cells are present.
D) Complement will be detected on red blood cells.

Question 32

A patient with a warm reacting autoantibody needs 2 units of compatible, packed cells. Medical history reveals a blood transfusion 2 months ago. A homologous absorption is performed using the following red blood cell phenotype: R²R², ss, Fy(a-b+), Jk(a+b-), kk. What alloantibody would remain in the serum after absorption?

A) anti-Jk^a
B) anti-E
C) anti-S
D) anti-Fy^b

Question 33

A benign cold autoagglutinin may cause interference in antibody screening procedures when:

A) anti-IgG AHG reagents are used in the test procedure.
B) polyspecific AHG reagents are used in the test procedure.
C) the immediate spin phase is omitted.
D) LISS is used as a potentiator at 37°C incubation.

Question 34

Which of the following is a characteristic red blood cell morphology seen on a peripheral blood smear from a patient with warm autoimmune hemolytic anemia?

A) Stomatocytes
B) Teardrop cells
C) Spherocytes
D) Target cells

Question 35

What is one indication a positive DAT might be due to alloantibody coating donor red blood cells?

A) Positive eluate
B) Positive rosette test
C) Microscopic mixed-field appearance
D) Panagglutinin reaction in panel studies

Question 36

Autoanti-I was identified in a patient transfused 1 month ago. Which technique is advocated to detect alloantibodies in this patient?

A) Cold autoabsorption
B) Prewarming
C) Warm autoabsorption
D) Enzyme treatment

Question 37

Anti-K was identified in absorbed serum of a patient with warm autoimmune hemolytic anemia. If a red blood cell phenotype was performed using an indirect antiglobulin test to ensure the patient was negative for K antigen, what would the technologist find?

A) A negative result after cells were treated with ficin
B) A positive result due to IgM coating cells
C) Patient would type negative for K antigen
D) A positive result due to IgG coating cells

Question 38

Persons diagnosed with pneumonia caused by Mycoplasma pneumoniae may produce a cold autoantibody with specificity.

A) anti-H
B) anti-i
C) anti-I
D) anti-P

Question 39

All of the following are classifications of immune hemolytic anemia except:

A) hyperimmune.
B) alloimmune.
C) autoimmune.
D) drug-induced.

Question 40

A cold antibody titer greater than at 4°C is characteristic of pathological CHD.

A) 64
B) 1,000
C) 256
D) 128

Question 41

What treatment for warm autoimmune hemolytic anemia aids in the reduction of antibody and removes a potent site of red blood cell damage and destruction?

A) Corticosteroids
B) Splenectomy
C) Immunosuppressive drugs
D) Transfusion

Question 42

All of the following are characteristics of benign cold autoagglutinins except:

A) Antibodies react best with ficin-treated cells.
B) Autoantibodies are of the IgM class.
C) Antibodies have a titer greater than 64 at 4°C..
D) Autoantibodies can activate complement in vitro

Question 43

Which of the following is a characteristic of autoantibodies?

A) The DAT is only reactive with anti-C3d.
B) Antibody consists of IgM immunoglobulin.
C) Antibody reacts with low-incidence antigens.
D) Antibody reacts with high-incidence antigens.

Question 44

What is the recommended treatment for drug-induced hemolytic anemia caused by the immune complex mechanism?

A) Splenectomy
B) Immunosuppressive therapy
C) Cessation of drug administration
D) Transfusion

Question 45

Which theory supports production of autoantibodies?

A) Loss of T-cell suppressor activity upon self-antigens leads to production of autoantibody.
B) Helper T cells assist immunocompetent B cells in making antibody against foreign antigens.
C) T suppressor cells prevent overproduction of antibody by B cells.
D) Loss of T helper cell activity upon self-antigens leads to production of autoantibodies.

Question 46

How can cold autoantibody interference with ABO grouping be avoided?

A) Washing cells with normal saline cooled to 4°C
B) Washing cells with normal saline warmed to 37°C
C) Treating red blood cells with ficin prior to testing
D) Washing cells with normal saline (room temperature)

Question 47

In which case might you see an anti-i?

A) Mononucleosis
B) Viral hepatitis
C) Paroxysmal nocturnal hemoglobinuria
D) None of the above

Question 48

Chemically modified anti-D reacted negatively in a patient with a warm-reacting autoantibody. A Du test was performed using monospecific IgG, which was positive in Coombs' phase. A fetal screen (rosette test) was also performed on this patient and showed no rosettes when viewed microscopically. Based on these results, what is the correct Rh type of this patient?

A) Rh-positive
B) Rh-negative
C) Rh-unknown
D) Du-positive

Question 49

Immune hemolytic anemia is defined as:

A) an increased RBC destruction caused by radiation exposure.
B) a shortened RBC survival caused by defective DNA synthesis.
C) a shortened RBC survival mediated through humoral antibody production.
D) an increased RBC destruction caused by enzyme defects.

Question 50

A 5-year-old boy suffering from the measles complained of back pain, chills, and stomach pain. A visit to the doctor revealed hemoglobinuria, bilirubinemia, and hemoglobinemia. The child's hemoglobin level had fallen to 6 g/dL. A Donath- Landsteiner test was performed and showed the following: control sample = no hemolysis; test sample = hemolysis. The results are consistent with what disorder?

A) Warm autoimmune hemolytic anemia
B) Cold hemagglutinin disease
C) Paroxysmal cold hemoglobinuria
D) Secondary cold AIHA

Question 51

Which cells contain the most i antigen?

A) Lymphocytes
B) Cord blood
C) Adult red blood cells
D) Platelets

Question 52

In cases of warm autoimmune hemolytic anemia, what subclass of IgG is most efficient in binding complement?

A) IgG₂
B) IgG₁
C) IgG₃
D) IgG₄

Question 53

Which of the following regarding the immune complex mechanism in serologic testing is true?

A) The antibody is directed against a red blood cell antigen.
B) The antibody screen will be positive in Coombs' phase.
C) The DAT will be positive with monospecific C3 but negative with IgG.
D) The eluate will be positive.

Question 54

Which of the following describes a cold autologous absorption procedure?

A) An aliquot of patient cells is incubated with an equal aliquot of patient serum at 37°C; autoantibody is removed and alloantibody remains in the serum.
B) An aliquot of patient cells is incubated with an equal aliquot of patient serum at 37°C; alloantibody is removed while autoantibody remains in the serum.
C) An aliquot of patient cells is incubated with an equal aliquot of patient serum at 4°C; alloantibody is removed while autoantibody remains in the serum.
D) An aliquot of patient cells is incubated with an equal aliquot of patient serum at 4°C; autoantibody is removed while alloantibody remains in the serum.

Question 55

Which of the following signifies intravascular hemolysis in AIHA?

A) Increased haptoglobin
B) Bilirubinemia
C) Hemoglobinuria
D) Spherocytosis

Question 56

Which drug-induced mechanism does not result in a hemolytic episode?

A) Immune complex formation
B) Drug adsorption
C) Membrane modification
D) Methyldopa-induced autoantibody

Question 57

Which of the following forward-typing reagents may generate false-positive results in a patient with a warm-reacting autoantibody?

A) Anti-A
B) Anti-B
C) Anti-A, B
D) Anti-D

Question 58

What is the mechanism by which thiol reagents, such as dithiothreitol (DTT), disperse agglutination caused by cold-reactive autoantibody?

A) Dissociation of IgG molecules from the red blood cell with no damage to the membrane
B) Cleavage of the intersubunit disulfide bonds of dimeric IgG molecules
C) Cleavage of the intersubunit disulfide bonds of pentameric IgM molecules
D) Dissociation of IgM molecules from the red blood cell with no damage to the membrane

Question 59

What reagent cell type is used in the immune complex formation test to detect drug-antidrug interaction?

A) Group A
B) Group B
C) Group AB
D) Group O

Question 60

What is the most frequent antibody specificity in CHD?

A) Anti-IH
B) Anti-i
C) Anti-I
D) Anti-P

Question 61

Approximately what percentage of warm autoimmune hemolytic anemia will produce a positive DAT with both IgG and C3d antibodies?

A) 20%
B) 67%
C) 10%
D) 13%

Question 62

An EDTA sample is preferred over a clotted sample for performing DAT testing because:

A) hemolysis is less likely to occur in a smaller EDTA tube.
B) complement coating is better detected in an EDTA tube.
C) the EDTA prevents complement binding in-vitro.
D) there is less likely to be fibrin in the EDTA tube.

Question 63

The antigen I is often:

A) found on all cord cells.
B) absent on all cord cells.
C) a rare antigen.
D) only found in the white population.

Question 64

A DAT was performed on a patient suspected of having autoimmune hemolytic anemia. The following results were obtained: PS AHG 3+, Anti-IgG 2+, Anti-C3d-negative. These results mean:

A) the test is invalid.
B) the patient's cells are coated with IgG.
C) the patient's cells are coated with C3d.
D) the patient's cells are coated with both IgG and C3d.

Question 65

A 28-year-old female with cold hemagglutinin disease has a positive DAT. When the DAT is repeated using monospecific reagent, which of the following is most likely to be detected?

A) IgM
B) IgG
C) C3d
D) C4d

Question 66

Cold panel results obtained are: A1 cells: 4+
A2 cells: 4+
O cells: 4+
O cord cells: 0
These results suggest which antibody?

A) H
B) IH
C) I
D) i