Ruling Out Antibodies - The Sequel!

[Malcolm Needs ☆]

I am going to put the cat amongst the pigeons here (not at all like me, I know)!

When you find an apparent anti-C+D in the plasma of a female patient of child bearing potential (I repeat, I hate that phrase, but it seems to be the "in thing" in the UK), how many of you would test the plsma to ensure that it really is anti-C+D, or whether it is actually anti-C+G or anti-G?

The reason I ask is because anti-C and/or anti-G are rarely the cause of clinically significant haemolytic disease of the newborn/foetus (although anti-G more commonly than anti-C), but anti-D most certainly is a cause of this. Therefore, any female with anti-G and/or anti-G+C should be offerred anti-D immunoglobulin prophylaxis when pregnant.

:confused::confused:

[clmergen]

It isn't written into our policy but a few months ago we had a pregnant female with an apparent anti-D+C. I sent that to our reference lab who had a single cell frozen that was D-C-G+. It didn't react so we called it an Anti-D+C.

(never would have crossed my mind before SBB school).

[David Saikin]

I can only check this out if I am lucky enough to have a rG cell amongst my panels cells. I have had a few which I have called anti-G, not anti-C,-D or -CD (is there such an animal?).

[Malcolm Needs ☆]

I can only check this out if I am lucky enough to have a rG cell amongst my panels cells. I have had a few which I have called anti-G, not anti-C,-D or -CD (is there such an animal?).

I meant anti-C+anti-D David, not a compound anti-CD!

Actually, you don't need an rG cell to show the presence of an anti-G (unless there is also both an anti-C and an anti-D present).

If you split the plasma sample into two, you can adsorb one with r'r red cells, which will take out anti-C and anti-G (but leave anti-D) and then test the adsorbed plasma with Ro red cells to show the presence of anti-D, and adsorb the other with Ro red cells, which will take out anti-D and anti-G (but leave anti-C) and then test this adsorbed plasma with r'r red cells to show the presence of anti-C.

If after adsorption, neither aliquot shows any reaction with their respective cells, then the antibody is a monospecific anti-G.

If the r'r red cells react with the plasma adsorbed with Ro red cells, and the Ro red cells react with the plasma adsorbed with r'r red cells, then there is an anti-C and an anti-D present (+/- an anti-G, but the anti-G would now be irrelevant).

:):)

[clmergen]

That's too much work.

[Malcolm Needs ☆]

That's too much work.

This is NOT something that I would advocate doing in all cases of suspected anti-C+D, and I certainly wouldn't suggest that it is something that could be done at most Hospital Blood Bank levels; most of them would not have sufficient r'r or Ro red cell samples to do this.

It is, however, something that I would expect all Reference Laboratories to be able (and willing) to do; but, once again, not in all cases of suspected anti-C+D in females of child bearing potential.

We would only do this if either the plasma reacted markedly more strongly with R1R1 than R2R2 red cells (a pretty good sign that you are looking at an anti-G or an anti-G+C) in the case of a female from 0 to 60 years, or if the partner is an r'r in the case of a pregnancy.

All that having been said, it does only take about a couple of hours to perform, and most of those couple of hours is incubation, so there is plenty of opportunity to get on with other things in the meantime.

The statement I would make is this.

If it were my wife (who happens to be rr) who was pregnant with an apparent anti-C+D (and I am an R1R1 incidentally), but her plasma reacted more strongly with R1R1 than R2R2 red cells, I sure would like to know the true specificity of the antibody, so that she could be offered anti-D immunoglobulin prophylaxis if she had yet to make an alloanti-D.

The chances of the anti-G or anti-G+C causing clinically significant HDNF are much, much smaller than anti-D. If we wanted another child, therefore, there would be less danger to both the fetus and my wife if she had not made anti-D as well.

:peaceman:

[clmergen]

I wasn't even considering the HDFN aspect of the problem. I wanted to know if the patient was a candidate for Rh Immune Globulin as this was discovered on a prenatal workup.

[Malcolm Needs ☆]

I think, if it was a pre-natal work-up, then it was worth doing, because the couple were obviously planning a pregnancy, but only from the point of view of anti-D immunoglobulin during the pregnancy as prophylaxis to prevent her making an anti-D of her own, if she hadn't already made one.