In warm autoimmune hemolytic anemia, the DAT is usually positive with:

Anti-IgG, with or without anti-C3

A patient on high-dose intravenous penicillin has a positive DAT with IgG. The eluate reacts only with penicillin-coated red cells. The mechanism is:

Nonimmunologic protein adsorption

A child on ceftriaxone develops sudden severe intravascular hemolysis. The DAT is positive for C3, and the patient's serum reacts with red cells only when ceftriaxone is added to the test. The mechanism is:

A drug-dependent antibody (drug in solution)

Drug adsorption onto the red cells (hapten)

Nonimmunologic protein adsorption

Induction of a true warm autoantibody

A patient with cold agglutinin disease needs red cells. The DAT is positive for C3 only. Which practice helps most?

Choose rare I-negative red cells

A patient with warm AIHA, transfused 2 weeks ago, needs blood. Which method should be used to look for alloantibodies hidden by the autoantibody?

Allogeneic adsorption with phenotyped cells

An eluate from the patient's red cells

Autoadsorption with the patient's own cells

Immune hemolytic anemias: warm, cold, drug-induced

9 ASCP MLS practice questions on Immune hemolytic anemias: warm, cold, drug-induced, part of Blood Banking. The first 9 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
In warm autoimmune hemolytic anemia, the DAT is usually positive with:
1. AAnti-C3 only
2. BAnti-IgG, with or without anti-C3
3. CAnti-IgM only
4. DNeither anti-IgG nor anti-C3
Show answerHide answer
Answer: B · Anti-IgG, with or without anti-C3
Warm autoantibodies are usually IgG, so the DAT is positive with anti-IgG, often with C3 as well. The coated cells are removed by splenic macrophages. An eluate typically reacts with all panel cells. Autoantibodies in the plasma can mask alloantibodies, which must be looked for.
- A: A C3-only DAT is typical of cold autoantibodies.
- C: Routine DAT reagents do not include anti-IgM.
- D: A negative DAT does not fit warm AIHA.
Question 2 · Medium
A patient on high-dose intravenous penicillin has a positive DAT with IgG. The eluate reacts only with penicillin-coated red cells. The mechanism is:
1. ADrug adsorption (hapten)
2. BDrug-dependent immune complex
3. CAutoantibody induction
4. DNonimmunologic protein adsorption
Show answerHide answer
Answer: A · Drug adsorption (hapten)
Penicillin binds firmly to the red cell membrane, and an IgG antibody to the drug coats the cells. The eluate reacts only with drug-treated cells, not with untreated cells. Hemolysis is usually extravascular and develops gradually at high doses. It stops when the drug is stopped.
- B: Immune-complex type antibodies react only when the drug is present in solution and often cause intravascular hemolysis.
- C: An induced autoantibody, as with methyldopa, reacts with untreated cells.
- D: Nonimmunologic adsorption coats cells with many proteins and rarely causes hemolysis.
Question 3 · Hard
A child on ceftriaxone develops sudden severe intravascular hemolysis. The DAT is positive for C3, and the patient's serum reacts with red cells only when ceftriaxone is added to the test. The mechanism is:
1. AA drug-dependent antibody (drug in solution)
2. BDrug adsorption onto the red cells (hapten)
3. CNonimmunologic protein adsorption
4. DInduction of a true warm autoantibody
Show answerHide answer
Answer: A · A drug-dependent antibody (drug in solution)
Some antibodies bind red cells only when the drug is present, forming complexes that activate complement. This mechanism, once called the immune-complex type, can cause sudden, severe intravascular hemolysis, kidney failure and death. Ceftriaxone and other cephalosporins are classic causes. The drug must be stopped and never given again.
- B: Hapten-type antibodies react with drug-coated cells and usually cause slow extravascular hemolysis.
- C: Nonimmunologic adsorption rarely causes hemolysis.
- D: A true autoantibody would react without the drug.
Question 4 · Hard
A patient with cold agglutinin disease needs red cells. The DAT is positive for C3 only. Which practice helps most?
1. AGive only group O red cells
2. BWarm the patient and the blood
3. CChoose rare I-negative red cells
4. DGive washed red cells
Show answerHide answer
Answer: B · Warm the patient and the blood
In cold agglutinin disease the autoantibody binds red cells in cooler parts of the body, so keeping the patient and the infused blood warm limits hemolysis. A blood warmer brings units to body temperature. I-negative blood is almost never available and is not needed. Washing is not usually required.
- A: The patient's own ABO group can be used; group O is not required.
- C: I-negative blood is extremely rare and not routinely needed.
- D: Washing does not prevent cold autoantibody binding.
Question 5 · Hard
A patient with warm AIHA, transfused 2 weeks ago, needs blood. Which method should be used to look for alloantibodies hidden by the autoantibody?
1. AAn eluate from the patient's red cells
2. BAutoadsorption with the patient's own cells
3. CCold autoadsorption at 4 °C
4. DAllogeneic adsorption with phenotyped cells
Show answerHide answer
Answer: D · Allogeneic adsorption with phenotyped cells
After a recent transfusion, the patient's sample contains donor red cells that could adsorb alloantibodies, so autoadsorption is not used within 3 months of transfusion. Instead, plasma is adsorbed with selected allogeneic cells of known phenotypes, often treated with ZZAP or enzymes. Alloantibodies stay in at least one adsorbed aliquot and can then be identified. Red cells are then chosen to lack the antigens of any alloantibodies found.
- A: An eluate shows the autoantibody, not hidden alloantibodies in the plasma.
- B: Recently transfused donor cells could remove alloantibodies during autoadsorption.
- C: Cold autoadsorption removes cold autoantibodies, not warm ones.
Question 6 · Medium
The blood film in warm autoimmune hemolytic anemia typically shows:
1. ASpherocytes and polychromasia
2. BSchistocytes and helmet cells
3. CBite cells and Heinz bodies
4. DTarget cells and Howell-Jolly bodies
Answer and explanation in LearnFree account
Question 7 · Medium
Which drug is classically linked to a true warm autoantibody, with a positive DAT and an eluate that reacts with all cells?
1. ACephalothin
2. BCeftriaxone
3. CPenicillin
4. DMethyldopa
Answer and explanation in LearnFree account
Question 8 · Hard
A 19-year-old college student with infectious mononucleosis (positive heterophile test) develops fatigue and dark urine. Results: hemoglobin 8.9 g/dL (89 g/L); reticulocytes 7.5%; LDH raised; haptoglobin below 10 mg/dL (0.1 g/L). The DAT is positive with anti-C3d and negative with anti-IgG. A cold-reacting autoantibody is found. At 4 °C, her plasma agglutinates adult group O cells 1+, group O cord cells 4+ and her own cells 1+. She takes no medicines and has never been transfused. The most likely autoantibody is:
1. AAnti-i, triggered by Epstein-Barr virus
2. BAnti-P, a biphasic Donath-Landsteiner antibody
3. CAnti-I, triggered by Epstein-Barr virus
4. DAnti-I, triggered by Mycoplasma pneumoniae
Answer and explanation in LearnFree account
Question 9 · Hard
A patient has a positive DAT with anti-IgG. Every panel cell and the autocontrol react at the antiglobulin phase, and an eluate reacts with all cells tested. Which procedure helps detect underlying alloantibodies before transfusion?
1. AAn immediate-spin crossmatch of all units
2. BAutoadsorption or allogeneic adsorption
3. CPrewarming the serum and cells
4. DNeutralization with secretor saliva
Answer and explanation in LearnFree account

Immune hemolytic anemias: warm, cold, drug-induced

In warm autoimmune hemolytic anemia, the DAT is usually positive with:

A patient on high-dose intravenous penicillin has a positive DAT with IgG. The eluate reacts only with penicillin-coated red cells. The mechanism is:

A child on ceftriaxone develops sudden severe intravascular hemolysis. The DAT is positive for C3, and the patient's serum reacts with red cells only when ceftriaxone is added to the test. The mechanism is:

A patient with cold agglutinin disease needs red cells. The DAT is positive for C3 only. Which practice helps most?

A patient with warm AIHA, transfused 2 weeks ago, needs blood. Which method should be used to look for alloantibodies hidden by the autoantibody?

The blood film in warm autoimmune hemolytic anemia typically shows:

Which drug is classically linked to a true warm autoantibody, with a positive DAT and an eluate that reacts with all cells?

A patient has a positive DAT with anti-IgG. Every panel cell and the autocontrol react at the antiglobulin phase, and an eluate reacts with all cells tested. Which procedure helps detect underlying alloantibodies before transfusion?