What is this antibody?

[adiescast]

We had a patient this week with an antibody that left me scratching my head. Caucasian male in for dialysis, B+, negative direct Coombs (Polyspecific, IgG, and C3), weakly reactive by solid phase (most cells 1+, one cell 2+, one cell W+) with a e (little e) pattern. Patient is negative for C (c untested), K, and Lea; positive for E, e, Leb, Jka, Jkb, Fya, Fyb, M, N, S, and P1.

We gave him C, e negative units, which he seems to have tolerated well. With the negative DAT, positive e antigen, and the caucasian race, it seemed unlikely to be a anti-e variant. He is almost certainly also c positive, so that would eliminate anti-f. I guess his Rh type as DcE/ce. Even if he had antibodies against all of the antigens he tested negative for, it would not match the pattern we saw.

Any thoughts?

[Yanxia]

adiescast，what about the transdusion hestory of this patient. I think some dialysis patient need to be transfused . If he has been transfused during the previous 3 month the antigen typing will need to careful the mix field. Would you do other medium other than solid phase to do the IAT. And as to the neg DAT, maybe elution will find something new to solve the problem.

I am a newcomer of this subject, just some idea, maybe not right, I also wish it can give you some help.

[Malcolm Needs ☆]

We had a patient this week with an antibody that left me scratching my head. Caucasian male in for dialysis, B+, negative direct Coombs (Polyspecific, IgG, and C3), weakly reactive by solid phase (most cells 1+, one cell 2+, one cell W+) with a e (little e) pattern. Patient is negative for C (c untested), K, and Lea; positive for E, e, Leb, Jka, Jkb, Fya, Fyb, M, N, S, and P1.

We gave him C, e negative units, which he seems to have tolerated well. With the negative DAT, positive e antigen, and the caucasian race, it seemed unlikely to be a anti-e variant. He is almost certainly also c positive, so that would eliminate anti-f. I guess his Rh type as DcE/ce. Even if he had antibodies against all of the antigens he tested negative for, it would not match the pattern we saw.

Any thoughts?

I think that it could still well be a very weak auto-anti-e-like antibody, even though the DAT is negative. Not all auto-antibodies cause a positive DAT (in the same way that not all positive DATs mean that the patient has a clinically-significant pathological condition), and the patient does not have to have a variant of the e antigen for him to have an auto-anti-e-like antibody.

One way of proving this is that you should be able to adsorb out the antibody using the patient's own enzyme-treated red cells and/or by using enzyme-treated R2R2 red cells.

[adiescast]

adiescast，what about the transdusion hestory of this patient. I think some dialysis patient need to be transfused . If he has been transfused during the previous 3 month the antigen typing will need to careful the mix field. Would you do other medium other than solid phase to do the IAT. And as to the neg DAT, maybe elution will find something new to solve the problem.

I am a newcomer of this subject, just some idea, maybe not right, I also wish it can give you some help.

We have a record of 10 red cell units transfused (which may not be a reliable total, since patients here sometimes go to other hospitals) with the last transfusion on October 4, 2010. The patient says the October date is correct, so we felt the antigen typings could be trusted.

We have used other methods for the IAT, but I did not see any reason to do so in this case because the antibody was so weak with the solid phase. We did not try an elution. Maybe I will try that on the next sample.

[Yanxia]

We have used other methods for the IAT, but I did not see any reason to do so in this case because the antibody was so weak with the solid phase。

adiescast, I am not familiar with the solid phase, I don't know it's sensitivity, I think no one method is sensitive to all antibodies, someantibodies will react better in other method than this.

If I encounter an antibody shows not clear patern, I will do different medium , different temperature incubation, adding the plasma to cells ratio etc.

:p:redface:

[adiescast]

Solid phase is pretty sensitive with most antibodies. I have found that anything less than a 2+ in solid phase simply will not show up in another enhancement. Possible exceptions are gel (which I don't have), PEG and enzymes. The confusion here had more to do with the pattern not making sense with the negative DAT rather than an unclear pattern. It was pretty clearly anti-e in a e positive patient with a negative DAT. If we get the same thing next time, I will try the elution as suggested. Probably if it is really a developing warm auto, it will be clearer next time anyway...

[GilTphoto]

Have you considered HTLA?

most cells weakly reactive at IAT and ruled out most significant antibodies by phenotyping. Is that correct?

Sounds like it's time to do a titer.

>=64, then it would be HTLA

Matching the pattern for e could just be coincidence, as the patient is e+

[Malcolm Needs ☆]

Have you considered HTLA?

most cells weakly reactive at IAT and ruled out most significant antibodies by phenotyping. Is that correct?

Sounds like it's time to do a titer.

>=64, then it would be HTLA

Matching the pattern for e could just be coincidence, as the patient is e+

Hmmm, I'm not sure about that.

I've seen plenty of "HTLA's" (proven single specificity) where the "HT" isn't (<16)!

:confuse::confuse:

Edited April 20, 2011 by Malcolm Needs

[adiescast]

The only titers we do are the standardized tube titers and this was likely negative in the tube, so the titer would have been zero.