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What is the minimum content of apheresis platelets?

Apheresis platelets must contain a minimum of 3.0 x 10^11 platelets.

What does the R1R1 phenotype indicate about Rh antigens?

R1R1 = DCe/DCe, so the person has D, C, e and lacks c and E.

What would a person with lele sese and H substance in secretions have?

H only in saliva, not Lea or Leb.

With which cells do antibodies that show dosage react strongest?

Homozygous antigen-positive cells rather than heterozygous cells.

Give an example of homozygous expression stronger for dosage.

Jk(a+b-) reacts stronger than Jk(a+b+) because Jk(a+b-) is homozygous for Jka.

What is the mechanism of PEG in antigen-antibody reactions?

PEG enhances antigen-antibody reactions by removing water from the test environment, concentrating antibody.

Is anti-HAV IgM routinely performed in donor testing?

No, it is not a routine donor screening test.

What are examples of routine hepatitis donor testing?

HBsAg, anti-HBc, anti-HCV, and NAT for HBV/HCV.

What does autocontrol test?

It tests the patient's own red cells with the patient's own plasma under the same conditions as the antibody screen.

How does autocontrol differ from DAT?

Autocontrol uses patient cells + patient plasma in vitro, while DAT detects antibody or complement already coating patient red cells in vivo.

What is the expression of I antigen on cord blood?

I antigen is absent or weak on cord blood cells; newborn cells are rich in i antigen.

How is I antigen expressed in adults?

I antigen becomes strongly expressed after birth as i converts to I.

Why is AB plasma considered the universal donor plasma?

It lacks anti-A and anti-B.

What is the purpose of anti-A,B reagent?

It helps detect weak A antigens and A subgroups.

How are weak D positive donors labeled?

They are labeled Rh positive for transfusion purposes.

Why are weak D donors labeled Rh positive?

Because donor red cells may express D antigen and could immunize an Rh-negative recipient.

What is the rule-out principle in antibody identification?

You rule out antibodies when panel cells negative for reaction carry the antigen, especially in homozygous form.

Why do homozygous cells matter in rule-outs?

They are preferred because dosage may make heterozygous cells react weakly or not at all.

Which antigens are enhanced by enzymes?

Kidd, Rh, Lewis, P1, and I are generally enhanced.

Which antigens are destroyed by enzymes?

Duffy and MNS antigens are generally destroyed or weakened.

How do Kell antigens react to enzymes?

Kell antigens are generally not destroyed by enzymes and are not enhanced.

What is the expiration period for frozen red cells?

Frozen RBCs may be stored up to 10 years when properly processed.

Which red cells does anti-H lectin react strongest with?

Group O red cells because they have the most H substance.

How do Bombay phenotype red cells react with anti-H lectin?

They do not react because they lack H antigen.

What phenotypes can result from AO x BO parents?

A, B, AB, or O offspring.

What is the 30-minute rule for blood return?

A blood unit may be returned to inventory only if it has been out of controlled storage for no more than 30 minutes.

Why can't a unit be reissued after improper storage?

If kept outside monitored storage for more than 30 minutes, it should not be returned to inventory.

What does antisera testing determine?

It determines phenotype, not genotype.

Why are low-frequency antigen antibodies often missed on screening?

They may not be detected by routine screening cells.

What are examples of IAT tests?

Antibody screen, antibody identification, and AHG crossmatch.

Which test is not an IAT?

DAT is not an IAT because it detects in-vivo coating of red cells.

What are common naturally occurring antibodies in never transfused, never pregnant patients?

Anti-M, anti-P1, anti-Lea, and anti-I.

What is the Rh genotype for D-, C+, c+, E-, e+, f+?

It is consistent with dCe/dce.

What does the f antigen indicate?

It is present when c and e are on the same haplotype.

How can anti-e be separated from anti-Fya?

Use an enzyme panel because anti-e is enhanced by enzymes while anti-Fya is destroyed.

What class is an antibody reacting only at AHG phase likely to be?

Most likely IgG.

What class is an antibody reacting mainly at immediate spin likely to be?

Usually IgM.

What is the most likely antibody for a cDe/cDe patient exposed to CDe/CDe cells?

Most likely stimulates anti-C.

What is the significance of a historic antibody?

Antigen-negative blood must still be selected even if the current screen is negative.

What is required for patients with a history of significant antibody?

They require an AHG crossmatch unless electronic crossmatch criteria are fully met.

What is required for patients with a history of significant antibodies?

An AHG crossmatch is required unless electronic crossmatch criteria are fully met.

What should be selected for a patient with a history of anti-E?

E-negative RBC units.

What is the safest uncrossmatched emergency blood type?

Group O Rh-negative RBCs.

How immunogenic is the K antigen?

K is highly immunogenic and clinically significant.

When are Kell antigens developed?

Kell antigens are well developed at birth.

What is the transfusion time limit for cryoprecipitate after pooling?

Cryoprecipitate must be transfused within 4 hours after thawing and pooling.

Why is washing important in AHG testing?

Washing removes unbound globulins that could neutralize AHG reagent and cause false negatives.

What should never be delayed in AHG testing?

AHG should be added immediately after washing and decanting.

Why can crossmatch be incompatible with a negative antibody screen?

The donor unit may have a positive DAT or the donor cells may be coated.

Where are MNS antigens located?

On glycophorin A and glycophorin B.

What antibody is ficin helpful in identifying?

Anti-Jka.

Who is a candidate for postpartum RhIG?

An Rh-negative mother with no true immune anti-D who delivers an Rh-positive infant.

What is the difference between passive anti-D and immune anti-D?

Passive anti-D does not prevent postpartum RhIG if indicated; true immune anti-D means RhIG is not useful.

Which antibody commonly causes delayed hemolytic transfusion reactions?

Anti-Jka.

Why are Kidd antibodies dangerous?

They may drop to undetectable levels and cause severe delayed hemolytic transfusion reactions.

Which antibody does not fit with Lea, P1, and i?

Anti-Jka does not fit because it is usually a warm-reactive clinically significant IgG antibody.

What does an anaphylactic reaction to transfusion with washed cells suggest?

The patient has anti-IgA and is IgA deficient.

Why do washed red cells help in IgA deficiency?

Washing removes donor plasma proteins including IgA.

How should a donor unit with a clinically significant alloantibody be handled?

It should not be used for transfusion of plasma-containing components.

How many units should be screened for an anti-K patient?

About 4 units on average should be screened.

What does polyspecific AHG contain?

Anti-IgG and anti-C3d.

What is the purpose of follow-up after a positive IAT?

To determine antibody specificity using reagent red cell panels.

What does anti-M reacting only with M+N- cells indicate?

It shows dosage, reacting more strongly with homozygous M-positive cells.

When is RhIG not indicated?

If the mother already has immune anti-D.

What percentage of the population is Rh positive?

About 85%.

What action should be taken with platelets that have visible clots?

Do not issue; quarantine the unit for further evaluation.

In which phenotype is anti-U most likely found?

Individuals of African ancestry with S-s- phenotype.

Why can S-s- individuals make anti-U?

U antigen is present on almost all cells except those lacking both S and s.

What should be done to confirm rouleaux causing false-positive IS crossmatch?

Perform saline replacement.

What blood group confers resistance to Plasmodium vivax?

Absence of Duffy antigen.

What is the best clerical error detection method in acute transfusion reactions?

Repeat ABO typing on pre- and posttransfusion samples.

What blood product modification is required for bone marrow transplant patients?

Irradiation to prevent transfusion-associated graft-versus-host disease.

What does Dolichos biflorus lectin do?

Agglutinates A1 cells.

How do A1 cells compare to O cells in H substance?

A1 cells have less H substance than O cells.

What is the definition of Bombay phenotype?

It lacks H antigen due to hh genotype.

What antibodies do Bombay individuals usually have?

Anti-H, anti-A, and anti-B.

What is the purpose of anti-A1 lectin?

To distinguish A1 from A2 and other A subgroups.

What does the secretor gene allow?

It allows soluble ABH substances to be present in secretions.

What are Lewis antigens?

They are adsorbed onto RBCs from plasma.

What is the effect of the lele genotype?

Individuals do not produce Lea or Leb substances.

What is the effect of the sese genotype?

Individuals are nonsecretors and do not secrete ABH substances into saliva.

What are common examples of dosage-associated antibodies?

Rh, Kidd, Duffy, and MNS antibodies.

What are common clinically significant warm antibodies?

Rh, Kell, Kidd, and Duffy antibodies.