phuluong2k
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Woman 32 y/O, G1 P0, Blood group B, Rh+, her husband blood group AB & Rh+
Although her child has a blood different from hers, alloimmunzation is of little concern because
A. Immune response is depressed in pregnancy
B. ABO antigens are weakly antigenic
C. Mother is tolerant to child's ABO antigens
D. Antibodies to ABO antigens do not cross the placenta.
E. Antibodies to ABO antigens are not hemolytic.
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| drkpp
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E.
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| nisha
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D
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| mani
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D. Antibodies to ABO antigens do not cross the placenta.
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| ARJ
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C. Mother is tolerant to child's ABO antigens
Because, suppose if there is ABO mismatch between the mother and the fetus. And if there is feto maternal bleed. .The Fetal RBC cells( antigen) which enters the maternal circulations are killed immediately by the circulating maternal antibobies.
My dear phulung plz give the answer
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| phuluong2k
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Sorry, in the question, the mother has blood group O
The given answer is D
UW explanation
ABO antibody is IgM, to bulky to cross placenta
Rh antibody is IgG, small enough to cross placenta.
I am not satistactory with the answer D. if ABO antibody can cross placenta why there is ABO hemolytic disease in neonate ?
O phenotype people have isohemagglutinins Anti A, B igM & Anti A, B IgG. So IgG can pass placenta and can cause hemolysis in the first newborn. (Rh antibody does not cause hemolysis in the first newborn).
I think it is better if the answer D say: "antibodies to ABO antigens cross the placenta incompletely "
What's your opinion ?
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| mani
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the explanation given is correct. I knew from my grauation classes that antibody agaisnt A/b antigens are IgM and against Rh factor it is IgG.
Hemolysis associated with ABO incompatibility is limited to type O mothers with fetuses who have type A or B blood. In mothers with type A and B blood, naturally occurring antibodies are of IgM class, which do not cross the placenta, whereas in type O mothers, the antibodies are predominantly IgG in nature. Because A and B antigens are widely expressed in a variety of tissues besides RBCs, only small portion of antibodies crossing the placenta is available to bind to fetal RBCs. In addition, fetal RBCs appear to have less surface expression of A or B antigen, resulting in few reactive sites—hence the low incidence of significant hemolysis in affected neonates.
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| phuluong2k
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The mother in this q has type O blood groups too.
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| phuluong2k
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UW Q.ID 2099
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| mani
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phuluong2k, i m sorry i didnt read ur post above that said that maternal blood group is O. I agree to ur comment that antibodies cross the placenta imcolpletely. Althogh low expression of fetal A/B antigens and binding of antibodies to the the tissues other than RBCs do contribute, but still the main factor is less Ab crossing the placenta
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| phuluong2k
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Mani, your explanation is helpful
Go ahead 
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| mani
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i hope it helped
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