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ABO & H Blood Groups Flashcards

(54 cards)

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1
Q

What is Landsteiner’s rule?

A

If you possess the red cell antigen (Ag), you will not have the antibody (AB)

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2
Q

What are the four major blood types in the ABO system?

A
  • A
  • B
  • AB
  • O
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3
Q

Which blood type is known as the universal donor for red cells?

A

Group O

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4
Q

Which blood type is known as the universal recipient for red cells?

A

Group AB

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5
Q

What are the immunoglobulin classes of ABO antibodies?

A
  • IgM
  • IgG
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6
Q

Define secretor and non-secretor.

A

Secretor: produces soluble A and B antigens in secretions. Non-secretor: does not produce these soluble antigens.

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7
Q

What is the effect of age on the production of ABO isoagglutinins?

A

Production of ABO isoagglutinins changes with age.

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8
Q

What is the purpose of lectins in transfusion science?

A

Lectins are used to identify blood group antigens.

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9
Q

What is forward typing in ABO/Rh typing?

A

Detects the presence or absence of A, B, and D antigens.

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10
Q

What is reverse typing in ABO serum typing?

A

Detects the presence or absence of ABO antibodies.

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11
Q

Fill in the blank: The source of antigen in routine testing can include __________.

A

Reagent, Patient red cells, Blood Donor

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12
Q

What are the sources of antibodies in routine testing?

A
  • Patient plasma/serum
  • Commercial anti-sera
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13
Q

What is the purpose of an antibody screen?

A

To detect pre-formed antibodies to red cell antigens.

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14
Q

What does phenotype testing detect?

A

The presence or absence of red cell antigens.

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15
Q

What is the difference between phenotype testing and genotype testing?

A

Phenotype testing detects physical expression of inherited traits; genotype testing determines actual genes inherited.

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16
Q

What is the principle of specificity in immunology?

A

The recognition of the antigen and its corresponding antibody molecule.

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17
Q

What does potency describe in agglutination reactions?

A

The strength of the agglutination reaction.

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18
Q

What is the frequency of blood type A in the ABO blood group?

A

40%

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19
Q

What is the frequency of blood type O in the ABO blood group?

A

45%

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20
Q

What immunoglobulin class do ABO antibodies belong to?

A

IgM

IgM antibodies are naturally occurring and do not require prior exposure to the antigen.

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21
Q

At what age do newborns begin to develop ABO antibodies?

A

3 to 6 months

ABO antibodies are not detected at birth but begin to develop shortly after.

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22
Q

What is the inheritance pattern of the ABO blood group system?

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A

Co-dominant

Both A and B alleles are expressed equally when inherited.

23
Q

What is the role of the H antigen in the ABO blood group system?

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A

Foundation for A and B antigens

The H antigen is necessary for the expression of A and B antigens.

24
Q

What is the dominant gene responsible for the H antigen?

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A

H gene

The H gene is inherited independently of the ABO antigens.

25
What are the immunodominant sugars for group A and B blood types?
* A: N-acetylgalactosamine * B: D-galactose ## Footnote These sugars determine the specificity of the ABO blood types.
26
What is the significance of the Se gene in relation to blood type antigens?
Controls secretion of ABO antigens into body fluids ## Footnote The Se gene affects the presence of soluble antigens in saliva, sweat, and other fluids.
27
Define a secretor in the context of the ABO blood group system.
An individual who secretes soluble A, B, or H antigens into body fluids ## Footnote Approximately 80% of the population are secretors.
28
What is the procedure for the inhibition neutralization test for detecting ABH substances in saliva?
Mix saliva with diluted anti-sera, incubate, and observe for agglutination ## Footnote The test determines secretor status based on the presence of soluble antigens.
29
True or False: Group O individuals have no A or B genes to convert the H antigen.
True ## Footnote This results in a high concentration of unconverted H antigens in group O individuals.
30
What is the expected result of the inhibition neutralization test for a non-secretor?
Positive for agglutination ## Footnote A non-secretor will not neutralize the commercial antisera, resulting in agglutination.
31
What is the function of the transferase enzyme coded by the A and B genes?
Adds specific sugars to the H antigen ## Footnote This action determines the specificity of the A and B blood group antigens.
32
What indicates a positive test (SECRETOR) in the agglutination test?
If any one of the tubes is NOT agglutinated ## Footnote This shows that the individual secretes A or B antigens.
33
What is the Bombay phenotype?
Rarest of rare blood groups characterized by the absence of H antigen ## Footnote Individuals with this phenotype cannot form A or B antigens.
34
What is the frequency of the Bombay phenotype?
More likely to occur in east Indians but still very rare ## Footnote It has also been reported in Caucasians, Japanese, and African Americans.
35
What is a characteristic of Bombay individuals regarding their RBCs?
They DO NOT react with anti-H lectin ## Footnote This is significant during transfusion compatibility testing.
36
What is the consequence of transfusing group O red cells to a Bombay patient?
Immediate red cell lysis ## Footnote This is due to the presence of potent anti-H antibodies.
37
What antibodies do Bombay individuals typically possess?
Anti-A, anti-B, and anti-H ## Footnote Their serum contains these antibodies, which react with common ABO blood groups.
38
What is the main feature of subgroup A3?
Mixed field (mf) reaction with anti-A and anti-A,B antisera ## Footnote This subgroup is quite rare.
39
What differentiates A1 and A2 subgroups?
Quantitative difference in antigen expression ## Footnote A1 individuals have approximately 2 million antigen sites per red cell, while A2 have about 500,000.
40
What percentage of A2 individuals produce anti-A1 antibody?
1% to 8% ## Footnote A2B individuals have a higher prevalence of 22% to 35% producing anti-A1.
41
What is a common cause of category I discrepancies?
Unexpected weakly reacting or missing reverse reactions ## Footnote Often seen in patients with depressed ABO antibody production.
42
What is Category I discrepancy in blood typing?
Weak or missing reverse reactions, commonly seen in newborns, elderly, patients with certain diseases, and those on immunosuppressive medications ## Footnote Category I discrepancies often arise from depressed ABO antibody production or inability to produce ABO antibodies.
43
What factors can lead to Category I discrepancies?
* Newborns (cord sample/heel sticks) * Elderly * Certain disease states (e.g., leukemia, lymphoma) * Immunosuppressive medication * Agammaglobulinemia or immunodeficiency diseases * Bone marrow or hematopoietic progenitor stem cell transplants * Diluted ABO antibodies due to plasma transfusion * ABO subgroups ## Footnote These factors contribute to discrepancies in blood typing results.
44
How can you resolve Category I discrepancies?
Patient history can assist in resolution. For newborns or patients under 6 months, reverse is NEVER tested. For elderly or hypogammaglobulinemia patients, enhance weak or missing reactions by incubating reverse tubes with A1 and B cells for an additional 15 to 30 minutes at RT, then centrifuge and re-read. ## Footnote If still negative, incubate at 4°C for 15 to 30 minutes including an auto control tube and O cell control.
45
What is chimerism?
Individuals displaying two distinct cell populations existing in one person ## Footnote Chimerism can be true or artificial, with true chimerism being rare and occurring primarily in twins.
46
What causes artificial chimerism?
* Transfusion of O red cells into A, B, or AB persons * Bone marrow or hematopoietic progenitor transplant of a different ABO type * Exchange transfusions in babies * Fetal-maternal bleed ## Footnote Artificial chimerism is common but not lifelong.
47
What is Category II discrepancy?
Weak or missing red cell antigens associated with unexpected forward reactions ## Footnote These discrepancies are least encountered.
48
What can cause weak or missing reactions in RBC grouping?
* Subgroups of A or B * Weakened A and B antigens in some leukemias * Acquired 'B' phenomenon ## Footnote Rarely, substances in plasma due to certain cancers can neutralize anti-A/anti-B antisera.
49
What is the acquired B phenomenon?
Occurs in group A patients with lower GI tract diseases, where the immunodominant sugar is altered ## Footnote This is due to the removal of the acetyl group from N-acetylgalactosamine, converting it into D-galactosamine.
50
How can Category III discrepancies be resolved?
Washing patient cells with 0.9% saline and retesting can resolve rouleaux formation ## Footnote Rouleaux formation appears as agglutination due to abnormal protein levels in plasma.
51
What is the difference between agglutination and rouleaux?
Agglutination is true clumping of cells, while rouleaux is stacking of red cells like coins ## Footnote Rouleaux can often be resolved by saline replacement techniques.
52
What is Category IV discrepancy?
Discrepancy between forward and reverse typing due to cold reacting autoantibodies, unexpected ABO isoagglutinins, or multiple ABO types from transfusion or transplant ## Footnote This category typically requires incubation and washing techniques to resolve.
53
How can you resolve Category IV discrepancies?
Incubate cells at 37°C, wash with saline, then repeat testing. If unresolved, treat cells with dithiothreitol (DTT) ## Footnote DTT disperses IgM agglutination.
54
What is the cis-AB phenotype?
A rare genetic condition where an individual inherits both A and B genes from one parent on the same chromosome ## Footnote This results in the presence of three ABO genes instead of two.

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