? A subgroup - what would you do

[janet]

We have a postpartum woman who we previously grouped as O Rh:positive (once by tube and once by gel). Both these historical results show negative with Anti-A and Anti-B, the reverse grouping is 2+ A cells and 4+ Bcells.

Today one of our new grads noted weak 1+ reaction with the Anti-A, reverse again 2+ with Acells (weaker when warmed). We recollected the patient and got same results. Anti-A1 lectin is negative so we're thinking it is a A subgroup with an Anti-A1 ..... but gel doesn't pick up this subgroup at all!?

We tried testing the patient plasma agianst two A units = one 1+ (weaker after warming) and the other negative.

We tested the patient cells against group O plasma and got the result of 1+.

My question: since the Anti-A1 is probably insignificant (decreases on warming) should we call her an A to prevent her getting group O plasma. This will be confusing when we group her on the Provue though....if we call her O and she received O plasma would it cause a reaction (was 1+ in tube).

[kslaforce]

You mentioned the patient is post partum. What is the baby type and status? Was there a large fetal maternal bleed? You could have a dual cell population causing this problem. If this is not the case and the patient is truly a weak A subgroup with anti-A1, I would document it as such in your records and transfuse O cells and A FFP. You could also flag the record to perform tube typing and not run on the ProVUE.

[janet]

I didn't consider a maternal-fetal bleed because the gel was so straight forward negative (mixed fields are usually obvious). Our samples were pre-delivery....at the time I wrote she was post partum. I did type the baby anyway = O.

Thanks!

[Hi-Freq]

Do you have any A2 cells on hand you could test her with? Just curious.

[NedB]

Warming Anti-A and Anti-B reactions is ill-advised. These reagents work best at room temperature or colder. We just had a donor with similar reactions, taking the Anti-A to AHG gave a 1+ (Anti-B=0, A1 Cells 2+ by IS and AHG, B Cells 4+ by IS and AHG). Donor's cells did not react with Anti-A,B (IS or AHG). My guess was that she is a chimera, producing souble A antigens which coat the red cells if not few frank type A cells. The amount of A antigen is probably sufficient to reduce the production of Anti-A hence the weak reaction with A1 cells. We created a Patient file on this donor to make sure she gets Type O blood and type A or AB plasma if she needs a transfusion.

[ckcheng]

Janet, historical reaction negative with anti-A and anti-B but 2+ with A cells (I believe it was A1 cells) and 4+ with B cells suggest of A subgroup. It was further proof by patient cells negative with A1 lectin.

Now patient red cell show 1+ weak reaction with anti-A but negative in historical, I think it is due to the clone of the antisera. I know some anti-A does not react with some type of A subgroup (like Ax), but some does react. For example Seraclone does react, but BioScot TL-lot does not react. So I suggest you to check the packing insert to see if it solve your questions.

If the patient does finally proof to be A subgroup with anti-A1, whether transfuse with group A donor blood and group A plasma or group O donor blood and group A plasma depends on your institute's policy and the method you do the crossmatch. Technical Manual says [anti-A1 usually reacts better or only at temperature well below 37C and is considered clinicaly insifnificant unless there is reactivity at 37C.] British recomanded you to test using 37C-IAT before you issure group specific red cells. If your transfusion center use computer crossmatch, I believe you can issue group A red cells if the anti-A1 is not reactive at 37C; but if your transfusion center use immediate spin (IS) to confirm ABO group before issue the donor blood, I am afraid you have no choice but to give group O cells.

Hope that helps.

CK Cheng, MSc, SBB(ASCP), CQA(ASQ)

HONG KONG

Jan 2009

[marilynm]

Do you have any of the Gamma-clone anti-A,B? that should react with the cells if it is an A subgroup.

Marilyn M

[Yanxia]

Sometimes pregnant can decrease the A and B expression of the RBCs. I think the reagent sensitivity is one reason and the pregnant is another.