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IMED2002 > Blood Groups > Flashcards

Blood Groups Flashcards

1
Q

When did the 1st successful blood transfusion happen? Who did it?

A

1818, by James Blundell

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2
Q

Who discovered blood groups?

A

Karl Landsteiner

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3
Q

In 1901 Karl Landsteiner discovered ABO blood groups through

A

Agglutination patterns: he noticed agglutination of blood when mixed with others

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4
Q

which blood groups did Karl Landsteiner discover?

A

A, B, C (O) blood groups identification

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5
Q

Group A blood has antibodies to…

A

Group B (anti B)

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6
Q

Group B blood has antibodies to…

A

Group A (anti A)

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7
Q

Group AB blood has antibodies to…

A

None

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8
Q

Group O blood has antibodies to…

A

Both A and B (anti A & B)

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9
Q

Which group’s plasma would be the best to give to any individual (fool-proof)?

A

Group AB, as it has no antibodies

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10
Q

Whose red blood cells would be the best to give to any individual (foolproof)?

A

Group O (no antigens)

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11
Q

Are there only ABO blood groups

A

No, there are many! Approx 400 blood groups

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12
Q

What is the basis of transfusion reactions?

A

Individuals who lack an antigen may produce antibodies if exposed to that antigen. Ab may cross the placenta and cause haemolytic disease in the newborn.

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13
Q

Where are ABO blood groups located and how are they inherited?

A

Presence of A, and B antigens on the red cell surface
A and B antigens present on RBC at birth
Mendelian inheritance

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14
Q

In the plasma/serum, there are anti A and B antibodies present, when…

A

Present if lack A and B antigens respectively
Naturally occurring
Appear after 3 months of birth

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15
Q

Biochemistry of ABO blood groups

A

There is only a minor difference between A and B antigens
Although immunologically quite distinct
They have the same backbone sugar molecule (H antigen), only the terminal sugar is different

A and B produced from the H gene
H gene encodes an enzyme that adds fucose (sugar) to the terminal sugar of a precursor substance (H antigen)
Blood groups A and B are “built on” H antigen
A and B genes encode enzymes that add a sugar to H

“A” gene codes for an enzyme (transferase) that adds N‐acetylgalactosamine to the terminal sugar of the H antigen
The “B” gene codes for an enzyme that adds D-galactose to the terminal sugar of the H antigen

3 allelic genes: A, B, O
A and B genes control synthesis of different enzymes
O is “null” – i.e. no enzyme produced from that allele

The enzymes are responsible for addition of specific carbohydrate residues onto a membrane glycoprotein (substance H)

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16
Q

How are the ABO blood groups inherited?

A

Autosomal dominant, mendalian inheritance of the ABO blood groups

Child blood group determined by parents

17
Q

What type of antibodies are anti-A and anti-B?

A

IgM antibodies
Naturally occurring: produced at 3-6 months
They rarely cross the placenta as they are big molecules (pentameric antibody)

18
Q

What can anti-A and B antibodies cause?

A

Anti-A and B antibodies can cause clinically significant problems:
Cause rapid intravascular haemolysis (within blood vessel)
Severe immediate transfusion reactions (intravascular)
Cause mild haemolytic disease of the newborn (Group O mother; Group A baby)

19
Q

What is the most frequent blood group? then?

A

O - 46%

O > A > B > AB

20
Q

What are the blood group frequencies for the rest of the blood groups:

A

A - 39%
B - 11%
AB - 4%

21
Q

How many antigens are present in the Rhesus Blood Group system?

A

40

22
Q

How does the rhesus blood group system work?

A

D gene is either present (RhD positive) or absent (RhD negative)

The presence or absence of D determines Rh positive or negative

23
Q

why is RhD important

A

Rhesus D is important

The RhD antigen is highly immunogenic (able provoke immune response)

Important in haemolytic disease of the newborn

24
Q

How many Australians are Rh(D) positive?

A

85% the D gene is present

25
Q

How many Australians are Rh(D) negative?

A

15% the D gene is absent

26
Q

Explain how Anti-D antibodies are formed?

A

Anti-D only occurs in Rh(D) negatives, after exposure to D antigen through blood - no naturally occurring antibody (like the ABO)

Then the body will always make it, the immune cells will remember and continue to make Anti-D

Important in women who are Rh(D) negative, carrying Rh(D) positive baby, cross-placental RBC exposure to D antigen, means she will make antibodies

Then that will be dangerous for her second child, as the anti-D antibodies may cross placenta into Rh(D) positive baby, can cause haemolytic disease of newborn

27
Q

What is Rh(D) typing?

A

Patient’s red cells are typed with anti-D to detect whether Rh(D) positive

Cells that do not agglutinate are Rh(D) negative

28
Q

What type of antibodies are Rh antibodies

A

They are IgG
Hence, smaller, easier to pass through the placenta unlike the IgM antibodies (ABO)
can cause haemolytic reactions & HDN

29
Q

what is a solution given to Rh-negative mothers, who are pregnant with Rh-positive baby

A

Anti-D Ig given to Rh(D) negative mothers after birth of Rh(D) positive infant (to prevent production of immune anti-D that can cause haemolysis in subsequent pregnancies)

The injection will destroy any RhD positive blood cells that may have crossed over into your bloodstream during the delivery. This means your blood won’t have a chance to produce antibodies and will significantly decrease the risk of your next baby having rhesus disease (profalactin)

30
Q

What are some other major blood group systems

A

Kell
Most people lack K antigen (90%), only 10% K positive
K antigen is immunogenic
Anti-K can cause haemolysis - if exposed to K blood

Duffy
Malaria invades RBC through Duffy antigen (Fy)

Kidd (Jk)
Antibodies can cause delayed haemolytic transfusion reactions
Exposure to kidd positive blood, whilst kidd negative
Memory cells remember, and make antibodies
Then poor response to transfusion in the future (unexpected)

Lewis

31
Q

How is blood grouping performed?

A

RBCs to top of microtube, incubate, centrifuge

Microtubes filled with gel and anti‐A or anti-B

Antibody binds to red cells blood group

Red cells agglutinate unable to move through gel

IMED2002 (12 decks)

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