Unexplained Anti-C

[gagpinks]

Hi Malcolm

 We have a case where 32 year old pregnant lady Oneg rr and her partner is R2r. Her antibody screen was negative  at 12 weeks, she has been given prophylactic anti-D at 19 weeks,  Now her antibody screen is Positive and look like she developed Anti-D(proph D) and Unexplained anti-C.

As far as we know this is her first pregnancy and no previous miscarriage or no transfusion history. How did she develop anti- C?Are Anti-D injection  pure anti-D or they can contain mixture of Rh antibody? Do you think anti-C could have come from Prophylactic anti-D injection.

[SBBGIRL]

Anti-C could possibly be anti-G, or, the father of the child may not be the partner . . . when the child is born, the CORD could be typed  for C to confirm.

Sounds like titers may be needed til delivery . . .

[OkayestSBB]

Do you use Rhophylac? In the package insert it says, "Rhophylac® can contain antibodies to other Rh antigens (e.g., anti-C antibodies), which might be detected by sensitive serological tests following administration"

[David Saikin]

Rhophylac may have anti-G in it - I know 'cuz I called them and asked.

[gagpinks]

Wouldn't Anti-G will develop following to exposure of C antigen?

[Malcolm Needs ☆]

I also think that the anti-C (or, possibly, weak anti-G) could well be as a result of the administration of Rhophylac.

 

I think it unlikely that the lady is producing an allo-anti-G of her own, as, although her partner's DcE haplotype will encode for the G antigen (having a serine residue at position 103), it is much, much more likely that she would produce an anti-D, instead of, or as well as, an anti-G, because the number of D sites per red cell produced by the DcE haplotype is the highest of all of the "common" Rh haplotypes.  In addition, of course, if the foetus has inherited the DcE haplotype from the father, the Rhophylac would clear any foetal red cells that have leaked into the maternal circulation, thus clearing both the possible D antigen and the possible G antigen at the same time.

 

As someone else pointed out, however, it could be that the putative father is not actually the biological father!

 

Whilst it is immensely flattering to have a question posed directly to me, I should point out that I am only one of many, many people who contribute to this site, and my opinions are no more valid than any other person who may reply to posts.

[MAGNUM]

Whilst it is immensely flattering to have a question posed directly to me, I should point out that I am only one of many, many people who contribute to this site, and my opinions are no more valid than any other person who may reply to posts.

 

But we sooooooooooooo rely on your infinite wealth of knowledge.

[David Saikin]

 

Whilst it is immensely flattering to have a question posed directly to me, I should point out that I am only one of many, many people who contribute to this site, and my opinions are no more valid than any other person who may reply to posts.

 

I don't know about that Malcolm - I think your contributions are "valider" than most.