Anti-D in weak D(type 2) patient?

[K@The_Dresdeners]

can a patient typed as weak D (type2) perform an Allo-Anti-D?

[Malcolm Needs ☆]

The very rare case has been reported, according to my friend and colleague Joyce Poole at the International Blood Group Reference Laboratory at Filton in the UK, although the anti-D produced is usually very weak itself.

When you consider how many people worldwide have the Weak D Type 2 phenotype, and how many times these individuals must have been transfused with D Positive blood or have had D Positive babies, and the fact that only very few of them have produced an alloanti-D, you begin to realise just what a rare event this is.

Having performed a risk/benefit analysis, we treat them as D Positive in the NHSBT.

[K@The_Dresdeners]

Thank you:)!

If there is an alloanti-D, would it look like an auto-antibody when the pt. was transfused with D pos RBCs in the past?

K.

[Malcolm Needs ☆]

It could do, but you also need to be careful that it wasn't an auto-anti-D in the first place. I am not saying that the anti-D was detectable before the last transfusion, but, on occasions, a transfusion can either stimulate a de novo autoantibody, or can stimulate an autoantibody that is too weak for easy detection to become more easily detectable.

If possible, give the patient rr red cells if he/she requires transfusion, and then perform a DAT and/or an eluation three months after the last transfusion. If you can elute anti-D after this length of time, it is probably an auto-anti-D (more common than a lot of people think). If you cannot elute anti-D, but anti-D is still detectable in the patient's plasma, it is probably an alloanti-D.

Edited May 23, 2012 by Malcolm Needs
Forgot part of what I was going to say. Head like a sieve.

[K@The_Dresdeners]

When the pt. will need more transfusions and we give rr red cells, could we try eluation 3 month after the last D pos.-transfusion, when DAT is still positive?

I think she requires more RBCs in the next time, so we probably won´t have a complete 3 month transfusion-free interval while she is in our hospital.

K.

[Malcolm Needs ☆]

Oh yes. Sorry, that is what I meant. Three months after the last transfusion of D Positive blood, rather than three months after the last transfusion. Sorry if I confused you.

[Mabel Adams]

I have seen a lot of weak warm auto antibodies in gel that seem to "prefer" D pos cells--often react more strongly with them. A true allo-anti-D shouldn't cause a pos DAT/Auto control, right? Although the patient could have a pos DAT that is not related to the other problems, I suppose.