Question about Antibodies

[Immunohematologist]

I am just wondering how it could be possible for a patient to have an Anti-D antibody and be Rh positive. To me, it doesn't make sense since the red cells have the correct antigens, with exposure, it should not induce a production of Anti-D antibodies. I have been trying to figure this out all day. I suppose if the person was weak D positive, then a response could be made from those that were not positive.

I'm so confused

[Eagle Eye]

Please review thread under immunohematology reference(it's on first page)..There is so much discussion going on regarding same topic.

Anti D antibodies in a D positive patient ! Input please !

[Mer]

1. Does the patient have ITP as a diagnosis? If so, they probably received WinRho, which makes an Rh Pos person have a positive D alloantibody.

2. Another reason can be if the person has a "partial D." This is when the red cells are mising portions of D through inheritance, which in turn, makes the allo-D through high-incident D antigens that are missing on their red cells.

How do you identify a partial D? If you work at a bigger hospital, they may have a "panel" of anti-D typing reagents...essentially this is a panel, just like a regular panel you would perform, but they are all different partial D's - in letters A through L. Panels like these are used for investiagional purposes only. We actually had a DIV (roman numeral D4) at our facility last week!! If you go to www.albabioscience.co.uk this shows you a bit more about this topic under products.

Mer

[jhaig]

We just had a patient taking WinRho for ITP last week. The patient was

O Pos with an Anti-D. There was some initial confusion until we saw the diagnosis.

I think it's also possible to carry an autoantibody with Anti-D specificity, but I've never actually seen this.

Partial D is also possible, but unless you have the correct anti-sera for testing, you may never know for sure.

[bldbnkr]

I am just wondering how it could be possible for a patient to have an Anti-D antibody and be Rh positive. To me, it doesn't make sense since the red cells have the correct antigens, with exposure, it should not induce a production of Anti-D antibodies. I have been trying to figure this out all day. I suppose if the person was weak D positive, then a response could be made from those that were not positive.

I'm so confused

Hi,

This is possible and I have seen it twice in my 31 years of working in the field. Both times the Rh positive person was full Rh positive and not a Weak D, and in one of the cases had been transfused. I checked with my pathologist at the time and it has something to do with being a "partial D" and being able to make immune Anti-D to the piece of the D antigen that the recipient lacks and the donor has. In each case I informed the ordering physician that the person needed to wear a medic alert bracelet that they should receive on Rh negative red cells.

[Melanie]

With the use of monoclonal anti-D there has been many more patients that have been tested as Rh positive that are actually missing part of the D antigen. They are fully capable of making an antibody to the missing peice which would react with all normal Rh positive cells. These reagents are great for donor populations and not so great for patient populations. WE have instituted a policy so when we test a patient and it reacts less than 2+, we call then Rh neg. They receive RhIg if needed and Rh neg units. WE notate in their computer record that they are "Rh variable" for future reference.