Transcript Blood Groups & Transfusions

Pages 349-353
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When blood is given intraveneously
 Usually donated blood
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Transfusions are given for:
 Blood loss due to injury
 Surgery
 To supplement your own blood
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Blood cells have their own antigens
 Genetically determined proteins
 Allows us to determine “self”; a form of self defense
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Transfusions must be compatible w/recipient
 Those individuals with the same antigens
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What happens if the blood is incompatible?
◦ Your body will assume the transfused blood is an
invader
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Antibodies will bind to the (foreign) antigens
on the donor RBC
 Antibodies are proteins specialized to recognize
foreign substances and provide immunity against
them
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Incompatible transfusions cause agglutination
◦ clumping of the foreign RBCs
 RBCs burst open! (hemolysis)
 releases hemoglobin into bloodstream
 Hemoglobin can block kidney tubules
 Can cause kidney failure and death
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Represented by multiple alleles
Two of these are co-dominant
The Rhesus factor is a protein that may exist
on the surface of the cell – this results in a
positive blood type
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The ABO Blood groups:
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Type
Type
Type
Type
A (Both A antigens)
B (Both B antigens)
AB (Both A and B antigens)
O (neither antigen is present; recessive)
Rh (rhesus) factor ( + or - ):
 Positive or negative for presence on the surface of
the RBC
 Pregnant women risk destruction of baby’s RBCs as the
body attempts to reject a baby that doesn’t match
mother’s rhesus factor
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Differences in Rh factor between baby and
mother
 Most of the time, the first baby is fine
 Antibodies are built up after first baby
 This makes the second pregnancy extremely high risk

If the baby survives pregnancy:
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the destruction of RBCs will result in:
 Hemolytic disease of the newborn
 Jaundice
 Anemia
 Enlarged liver/spleen
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To counteract this problem:
◦ Incompatible mothers are given an immune serum
called RhoGAM to prevent this immune response