We have a patient that we transfused last year that was B positive. He recently had a bone marrow transplant and now forward types O positve and back types B positive. I understand that the O positive is from the donor's bone marrow and the lack of Anti-B is own. I am unsure what type to call him now. We were thinking of calling him O positive. We want to give him O packed cells but B or AB FFP. Is this right? What do the rest of you do?

antrita

We have a patient that we transfused last year that was B positive. He recently had a bone marrow transplant and now forward types O positve and back types B positive. I understand that the O positive is from the donor's bone marrow and the lack of Anti-B is own. I am unsure what type to call him now. We were thinking of calling him O positive. We want to give him O packed cells but B or AB FFP. Is this right? What do the rest of you do?

antrita

By that, do you mean that the patient's plasma contains anti-A, but not anti-B? If so, try Lewis typing them. If they are Le(a-b+) [or, come to that, they are Le(a-b-), but can be proved to be a secretor by testin their saliva] I wouldn't be too surprised.

All that is happening is that the Type 1sugar backbones from the plasma are being adsorbed onto the surface of the red cell. These continue to be "made" after a BMT and remain the same type as the recipient, however successful the BMT may be.

In other words, in your case, although the red cells may no longer be expressing the Type 2 group B backbones that are intrinsic to the red cell membrane, there will still be group B substance in the plasma, and this will "prevent" (to a large extent anyway) the recipient's immune system from recognising the B antigen as "foreign" and, therefore, he/she will not make anti-B.

The alternative theory is that the recipient does make anti-B, but that it is inhibited by the soluble Type 1 B antigen.

In either case, the chances are that your recipient has fully converted (or, at least, fully converted as much as they are ever going to convert) to group O, and can be safely treated as a group O from the FFP point-of-view.

For more information, if you can still get hold of it, see Needs ME, McCarthy DM, Barrett AJ. ABH and Lewis Antigen and Antibody Expression after Bone Marrow Transplantation. Acta Haematologica 1987; 78: 13-16 (written when I was but a callow youth - I wish)!!!!!!!!!

:D:D:D:D

When we back type this patient he has an Anti-A but no Anti-B. Our computer system doesn't like it when our forward type (in his case = O pos) and the back type (in his case Anti-A no Anti-. So part of our problem is it can't calculate a blood type and it (the computer) knows this patient as B positive. I think it will let be override the lack of Anti-A on an O positive patient. I wanted to just change him to O positive but my pathologist wants to wait till he comes back in (I am not sure why). Thank you for the information about the FFP, it just made me nervous because of the B positive history.

We are not a large hospital and this is the 2nd blood type change from a bone marrow transplant I've seen.

Antrita

We usually call the patient what (s)he is becoming (donor group) when the forward type converts. We do, however, continue to give plasma products based on the current observed reverse type. Unless you end up in a massive transfusion situation or your institution does not carry much plasma, it is not too hard to do this. We just put a note in the patient's file to alert the next tech. I would not give him AB plasma unless you had to. That seems a real waste when you might need it for someone who is AB (or unknown). I'd rather go with Malcolm's idea and give type O if you don't have any B.

But if we give this patient type 0 plasma, the anti-B with bind the B substance in his plasma and the immune complex can bind the receptor on immune cells, this can reduce the recepient's immune ability. Or the IC sedimentation cause hypersensitivity. This is just my guess, it is maybe not true.

But if we give this patient type 0 plasma, the anti-B with bind the B substance in his plasma and the immune complex can bind the receptor on immune cells, this can reduce the recepient's immune ability. Or the IC sedimentation cause hypersensitivity. This is just my guess, it is maybe not true.

In theory, you are absolutely correct, but, in practice, it is actually as safe as houses.

:):)

Malcolm, I am very respect of you in this field. But in this question, I disagree with you unless there are some date support you . I am sorry!

Malcolm, I am very respect of you in this field. But in this question, I disagree with you unless there are some date support you . I am sorry!

Don't apologise shily; I am never going to claim that I am correct in all things!

I don't have any hard and fast data on this, but what I will say is that we would often transfuse ABO incompatible platelets when HLA-matched platelets are required, when no ABO compatible platelets are available, or ABO incompatible IgA-deficient FFP when no ABO compatible IgA-deficient FFP is available, and I have never seen (or heard of) any reaction due to immune complexes in such patients (here, I am not talking about haemolytic transfusion reactions due to the antibody in the plasma reacting with the recipient's red cells, where the ABO antibodies are of high titre and the recipient is of small stature - a neonate or similar - which, of course, is well recorded in the literature, but antibodies complexing with soluble ABO substance). This is a particularly common occurrance in the case of patients who are group AB and require HLA-matched platelets or IgA-deficient FFP.

:confused::confused:

I have to go with Malcolm on this one. The risk is more theoretical than practical (unless you have some actual examples, Shily?). People everywhere take this risk on a regular basis when they transfuse out of type apheresed platelets (not that it is a good idea, but most do it because there was no choice). As I said in my previous post, we would choose B plasma first if we had it (which we almost always do).

There is an overview of "ABO Mismatched Allogeneic Blood and Marrow Transplants" at:

http://www.clinlabnavigator.com/transfusion/abomismatched.html

There is a lot of good material on this website.

Very nice, concise article, dmpollock. Thanks!