Erythroblastosis Fetalis Question

[PreMedStudent]

Hello there,

I was searching the other threads and couldn't find the answer to this simple question regarding Erythroblastosis Fetalis.

Q: What if the mother is Rh+ and the fetus is Rh- Does the same process of attack occur and if not why? I cannot seem to find anything, although i read somewhere that nothing happens if the mother is Rh+ and the fetus Rh-, Why is that?

Thanks in advance

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[robu058]

Hello there,

I was searching the other threads and couldn't find the answer to this simple question regarding Erythroblastosis Fetalis.

Q: What if the mother is Rh+ and the fetus is Rh- Does the same process of attack occur and if not why? I cannot seem to find anything, although i read somewhere that nothing happens if the mother is Rh+ and the fetus Rh-, Why is that?

Thanks in advance

It is my understanding that if this was the first pregnancy and she is Rh- and the fetus is not, nothing would happen. However, all bet are off if the same scenario repeats itself for a second pregnancy. This is because after the initial exposure, the mother immune system will generate anti-Rh antibodies that can cross the placenta and attack the fetus. To answer your question, if this is the inverse where the mother is Rh+ and the fetus is not, nothing would happen. This is because it would be the first time the fetus' immune system is exposed to a Rh antigen (mother's). It requires a second exposure or more to have Erythroblastosis!!

 

[DoctwoB]

Hello there,

I was searching the other threads and couldn't find the answer to this simple question regarding Erythroblastosis Fetalis.

Q: What if the mother is Rh+ and the fetus is Rh- Does the same process of attack occur and if not why? I cannot seem to find anything, although i read somewhere that nothing happens if the mother is Rh+ and the fetus Rh-, Why is that?

Thanks in advance

Erythroblastosis fetalis is a type II hypersensitivity rxn, in which Maternal anti-Rh IgG crosses the placenta and attacks the fetal red blood cells that are Rh+.

If the mother is Rh+, then she will not produce anti Rh antibodies, and EB will not occur.

It is similar to blood types, in that O (e.g. Rh -) will react to A (e.g. Rh+), but A will not react to O.

 

[PreMedStudent]

Thank You that clarifies everything now!!!!

 

[engineeredout]

Just to add on, if you have an ABO incompatibility and an Rh incompatibility, it is unlikely that the mother will become sensitized after the first pregnancy because, say the mother is O- and the baby is A+, if any of the A blood gets into the mother it will be automatically hemolyzed with preformed anti-A Igs, so there won't be time to develop an Rh antibody. Future pregnancies will be okay because the Anti-A or Anti-B is an IgM so it won't cross the placenta, and the IgG for Rh is never made.

 

[robu058]

Erythroblastosis fetalis is a type II hypersensitivity rxn, in which Maternal anti-Rh IgG crosses the placenta and attacks the fetal red blood cells that are Rh+.

If the mother is Rh+, then she will not produce anti Rh antibodies, and EB will not occur.

It is similar to blood types, in that O (e.g. Rh -) will react to A (e.g. Rh+), but A will not react to O.

Though your explanation is the correct and simple, I see the OP question differently. In OP mind, I think he wanna know if there is a reciprocity effect. That is, whether the mother being Rh- and having being previously exposed to Rh antigen would produce anti-Rh antibodies that would cross the placenta and causes damage (Erythroblastosis ) if the baby has the Rh antigen or is Rh+. And his question is if the baby is Rh- whether he would secrete anti Rh antibodies that would cross the placenta (in reverse) and cause the same thing to the mother's side: the reciprocity effect. The answer is no because the baby immune response has not been previously exposed to a Rh antigen and thus it would not lead to Erythroblastosis on the mother's side.

It's funny that here we have same question, same bottom line, but two different explanations.

 

[DrDrToBe]

Though your explanation is the correct and simple, I see the OP question differently. In OP mind, I think he wanna know if there is a reciprocity effect. That is, whether the mother being Rh- and having being previously exposed to Rh antigen would produce anti-Rh antibodies that would cross the placenta and causes damage (Erythroblastosis ) if the baby has the Rh antigen or is Rh+. And his question is if the baby is Rh- whether he would secrete anti Rh antibodies that would cross the placenta (in reverse) and cause the same thing to the mother's side: the reciprocity effect. The answer is no because the baby immune response has not been previously exposed to a Rh antigen and thus it would not lead to Erythroblastosis on the mother's side.

It's funny that here we have same question, same bottom line, but two different explanations.

The baby doesn't have antibodies of his own in utero, so no the baby can't induce erythroblastosis to the Mom. 😎

 

[robu058]

The baby doesn't have antibodies of his own in utero, so no the baby can't induce erythroblastosis to the Mom. 😎

are you dyslectic? Did you read the last sentence of the first paragraph???? It's staring right at your eyes!!

 

[DrDrToBe]

are you dyslectic? Did you read the last sentence of the first paragraph???? It's staring right at your eyes!!

Whether or not I am not dyslectic is not the point here, now is it? My point is that whether or not the baby was previously exposed is a non-issue since the baby wouldn't be making antibodies until ~6months after he's born. Sheesh!

 

[weightyheart]

are you dyslectic? Did you read the last sentence of the first paragraph???? It's staring right at your eyes!!

And his question is if the baby is Rh- whether he would secrete anti Rh antibodies that would cross the placenta (in reverse) and cause the same thing to the mother's side: the reciprocity effect. The answer is no because the baby immune response has not been previously exposed to a Rh antigen and thus it would not lead to Erythroblastosis on the mother's side.

doctwo8 is right.

robu058 is wrong. it doesn't matter if the fetus has been exposed once or 20 times before, fetii don't produce their own antibodies. and even if the baby were somehow to produce IgG antibodies, i don't understand how it is going to cause erythroblastosis fetalis in the mother as you state. maybe some hemolysis though.

 

[PreMedStudent]

Thank you everyone for your insight 🙂