The patient has a weakly reactive Jka that is of course enhanced with Ficin.  The patient's auto control is weakly positive.  The DAT is completely negative.  The patient hasn't been transfused since 2012.  The patient's antigen typing is 3+.  Advice please!! 

Possibilities:

1.  Auto anti-Jka (have been documented)

2.  The patient is a Jka variant with allo-anti-Jka

3.  Patient has a BM transplant

4.  The antibody is not a real anti-Jka.  (There is a type of pseudo anti-Jka that is dependent on parabens for its activity.  Depending on the method you are using to do your antibody screens, this might be probability no.1)

5.  Something else that I haven't thought of!

To do:

1.  Check patient's records for eventual bone marrow or stem cell transplantation.

2.  If possible, repeat the antibody screen with cells and methods from different manufacturers

3.  Repeat antigen typing and if necessary molecular biology.

In the meantime, and provided he is Jkb+, transfuse with Jka-b+ blood. 

 

Hope this helps

anna

I agree 100% with Anna.

We actually see a few of these every year.

The only thing that I would say is that variant Jk(a) antigens are few and far between, and usually result in considerable weakening of the Jk(a) antigen. In this case, your results point to a normal expression of the antigen.

The reason that Jk(a) variants tend to weaken the antigen expression is because of the way the amino acid residue that produces the antigen is very close to the red cell membrane and is"semi-hidden" by the third external loop (see the attached diagram).Kidd Molecule.ppt

My next question is would an elution be necessary to call this an auto Anti-Jka?? By the way, you guys are awesome with your answers!

Edited April 15, 201411 yr by kmmoton

Yes, is the simple answer kmmoton, but be careful.  As you are no doubt aware, anti-Jka can be extremely labile, and will find any excuse not to play by the rules!!!!!!!!!!!!!!!!!!!!

We had a patient years ago with a clearcut anti-Jka + E in serum and eluate. Kind of looked like a delayed rxn at first, but he was 33 with no history of transfusion and the antigen typings were pretty strongly positive. I don't think steroids helped him much; after a week or two they took his spleen out.

The patient has a syngen graft  (HSCT: Febr. 2011.). She has now  an auto-anti-Jka with differential absorption. The DAT is 4+ (covered with IgG, C3d). The Jka antigen typing is 3+ (with monoclonal reagent), Jkb antigen negativ. The patient hasn't been transfused within 3 months.

What would you advise if the patient need to be transfused?

I would not hesitate to give Jk(a+b-) blood, but, given that the Jk( antigen is not particularly immunogenic, I would also not hesitate to give Jk(a+b+) or Jk(a-b+) blood.

 

I think the clue is in the fact that your patient has an auto-anti-Jka, has (by now) 100% Jk(a+b-) red cells in his or her circulation, but has not required a transfusion for 3 months.  In other words, Jk(a+b-) red cells seem to survive quite nicely in their circulation!

Sorry to be thick - what is a syngen graft?

The donor is her identical twin.

Thank you.  

Anna

With a completely negative DAT would you find anything in an elution??

You could do, although this is not a given.

Thanks Malcolm