Reagent red cells have a much shorter shelf life than most antisera. The main reason is that during storage:

Red cell antigens weaken and the cells slowly hemolyze

The cells become coated with IgG from the preservative

Red cell antigens grow stronger and cause false positives

The suspension concentrates as the water evaporates

A technologist interprets today's panel using the antigen sheet (antigram) from the previous lot of panel cells. What is the main risk?

Wrong rule-outs, because cell phenotypes differ between lots

The reaction strengths will be graded too high

No risk, as all lots carry the same donor phenotypes

Only the autocontrol result becomes invalid

A vial of antibody screening cells, within its expiry date, has a dark red supernatant, and the cells look clumped after gentle mixing. What should be done?

Discard it and use a fresh vial

Use it only for patients with no antibodies

Use it, as the antigens are unaffected

Blood bank reagents and quality control

9 DOH Abu Dhabi (HAAD) lab licensing practice questions on Blood bank reagents and quality control, 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
Unless the package insert states otherwise, antisera and reagent red cells are stored at:
1. A-20 °C or colder
2. B35 to 37 °C
3. C20 to 24 °C
4. D2 to 8 °C
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Answer: D · 2 to 8 °C
Blood bank reagents are refrigerated at 2 to 8 °C and must not be frozen, which would lyse reagent red cells. Keeping them at room temperature speeds the loss of antibody activity and antigen strength and lets bacteria grow. Reagents are taken out only for use and returned promptly. Refrigerator temperatures are monitored and recorded as part of quality control.
- A: Freezing lyses reagent red cells and is not used for routine reagents.
- B: 37 °C is the incubation temperature for tests, not a storage temperature.
- C: Room temperature speeds deterioration and bacterial growth.
Question 2 · Medium
Reagent red cells have a much shorter shelf life than most antisera. The main reason is that during storage:
1. ARed cell antigens weaken and the cells slowly hemolyze
2. BThe cells become coated with IgG from the preservative
3. CRed cell antigens grow stronger and cause false positives
4. DThe suspension concentrates as the water evaporates
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Answer: A · Red cell antigens weaken and the cells slowly hemolyze
Reagent red cells are cells kept in a preservative solution, and some of their antigens weaken during storage. Aging cells also hemolyze, and weakened antigens can lead to false-negative antibody screens. Antisera are proteins that stay stable much longer when refrigerated. Daily QC and using cells within their dating guard against these losses.
- B: The preservative contains no IgG and does not coat the cells.
- C: Antigens weaken, not strengthen, as reagent cells age.
- D: Evaporation is not the reason for the short dating.
Question 3 · Easy
For tube agglutination tests, red cells are usually suspended in saline at a concentration of:
1. A2 to 5%
2. B40 to 50%
3. C20 to 25%
4. D0.8 to 1%
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Answer: A · 2 to 5%
A 2 to 5% suspension gives the right balance of antigen and antibody for tube tests. Too many cells can mask weak reactions, and too few make the cell button hard to read. Column agglutination (gel) cards use a weaker suspension of about 0.8 to 1%. Commercial reagent red cells are supplied ready to use at the strength stated in the package insert.
- B: A 40 to 50% suspension is close to whole blood and would mask weak reactions.
- C: A 20 to 25% suspension has far too many cells for tube tests.
- D: 0.8 to 1% is the suspension used in column agglutination (gel) tests.
Question 4 · Medium
A technologist interprets today's panel using the antigen sheet (antigram) from the previous lot of panel cells. What is the main risk?
1. AThe reaction strengths will be graded too high
2. BNo risk, as all lots carry the same donor phenotypes
3. CWrong rule-outs, because cell phenotypes differ between lots
4. DOnly the autocontrol result becomes invalid
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Answer: C · Wrong rule-outs, because cell phenotypes differ between lots
Each lot of panel cells comes from different donors, so cell 3 in one lot has no relation to cell 3 in the next. Reading reactions against the wrong antigram can exclude an antibody that is present or name one that is not. The antigram's lot number must match the vials in use and should be checked before interpretation. Recording the lot number on the worksheet makes this check routine.
- A: Grading of reactions does not depend on the antigen sheet.
- B: Panel lots come from different donors, so their phenotypes differ.
- D: The autocontrol uses the patient's own cells and does not depend on the antigram.
Question 5 · Medium
A vial of antibody screening cells, within its expiry date, has a dark red supernatant, and the cells look clumped after gentle mixing. What should be done?
1. AUse it only for patients with no antibodies
2. BDiscard it and use a fresh vial
3. CUse it, as the antigens are unaffected
4. DWash the cells, then use them
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Answer: B · Discard it and use a fresh vial
Marked hemolysis or clumping that does not disperse suggests bacterial contamination or deterioration, even before the expiry date. Damaged cells can lose antigen strength and give false-negative screens, or clump and give false positives. Every reagent is inspected before use, and an unacceptable one is discarded and the problem recorded. Results obtained with it should be reviewed.
- A: A false-negative screen would harm exactly the patients whose antibodies are missed.
- C: Hemolysis and clumping can come with loss of antigen strength.
- D: Washing does not restore damaged antigens or remove contamination.
Question 6 · Medium
For daily QC of anti-Jka antiserum, which positive control cell gives the best check of reagent strength?
1. AA Jk(a+b-) cell, with a double dose of Jka
2. BA Jk(a-b-) cell, which lacks both antigens
3. CA Jk(a+b+) cell, with a single dose of Jka
4. DA Jk(a-b+) cell, which lacks Jka
Answer and explanation in LearnFree account
Question 7 · Hard
Daily QC of the tube LISS antibody screen uses a weak anti-D control serum. Today the D-positive screening cells give 0 with it at the AHG phase, and a new vial of control serum gives the same result. Check cells added to these tubes react 2+. The most likely cause is:
1. AA fault in the sensitization (37 °C incubation) step
2. BAn inactive anti-IgG reagent
3. CContamination of AHG with human serum
4. DPoor washing that neutralized the AHG
Answer and explanation in LearnFree account
Question 8 · Easy
IgG-sensitized check cells used in antiglobulin testing are usually made by coating:
1. AGroup O red cells with IgM anti-A
2. BGroup A red cells with complement only
3. CD-positive red cells with IgG anti-D
4. DD-negative red cells with IgG anti-D
Answer and explanation in LearnFree account
Question 9 · Easy
Daily quality control of an anti-D typing reagent should include:
1. AThe first patient sample of the day
2. BA D-positive cell and a D-negative cell
3. CTwo D-positive cells of different strength
4. DA D-negative cell only
Answer and explanation in LearnFree account

Blood bank reagents and quality control

Unless the package insert states otherwise, antisera and reagent red cells are stored at:

Reagent red cells have a much shorter shelf life than most antisera. The main reason is that during storage:

For tube agglutination tests, red cells are usually suspended in saline at a concentration of:

A technologist interprets today's panel using the antigen sheet (antigram) from the previous lot of panel cells. What is the main risk?

A vial of antibody screening cells, within its expiry date, has a dark red supernatant, and the cells look clumped after gentle mixing. What should be done?

For daily QC of anti-Jka antiserum, which positive control cell gives the best check of reagent strength?

Daily QC of the tube LISS antibody screen uses a weak anti-D control serum. Today the D-positive screening cells give 0 with it at the AHG phase, and a new vial of control serum gives the same result. Check cells added to these tubes react 2+. The most likely cause is:

IgG-sensitized check cells used in antiglobulin testing are usually made by coating:

Daily quality control of an anti-D typing reagent should include: