ABO discrepancy; unusual results. What do you think...?

[Fluffy agglutinates]

Ok here goes...

Patient referred as 'Group O, no anti-B' (first thought is - well that's not a group O then!)

Pregnant. Ethnicity possibly Chinese descent. Not ill (this is an antenatal sample).

Antibody Screen Negative.

Forward group - O

Reverse Group - B (i.e. has anti-A but no anti-. Anti-A is 4+ reaction.

Patient red cells are negative with anti-A,B (commercial) & anti-H

Patient plasma is negative with O cells (4oC/ 22oC/ 37oC)

Adsorption/ Elution with anti-B is 'negative' - patient is not a B el

Secretion Test - 'no inhibition'

The closest match I can make with these results is a B hm BUT you would expect the anti-B & A,B to react weakly or, if not, be able to get a positive using the adsorption/ elution method.

Any thoughts anyone? I'm puzzilified!

[Malcolm Needs ☆]

Hi Fluffy agglutinates,

The result with the anti-H is the really puzzling one for me.

Yes, the ethnicity "fits" for a sub-group of B, but even with a group A1 or a group A1B you would expect some sort of weak reaction with anti-H.

Could you tell me at what temperature the patient's red cells were incubated with the anti-B and anti-A,B, whether the anti-A,B was a genuine anti-A,B, or was it a mixture of monoclonal anti-A and monoclonal anti-B, were the patient's red cells enzyme-treated and the tests repeated and what method was used for the elution (heat, acid, alkaline, Lui)?

Lots of questions I know, but the answers will all give clues.

...but I am puzzled by the reaction with the anti-H.

Could be your suspicion of a Bmh is correct! HIGHLY unusual!

By the way, do you know the answer, and has the sample been sent to Joyce?

:confused::confused:

[adiescast]

Possibly stupid question: could the failure to absorb and elute be from having too little antigen and insufficiently avid antibody? It sounds like she must have some tiny amount of B substance that prevents her from making anti-B.

Maybe some molecular testing or genetic testing could help.

A family study would be interesting.

[Malcolm Needs ☆]

By the way, what is the lady's Lewis type?

I am intrigued by this one!

[Fluffy agglutinates]

Hi Malcolm, indeed this is an interesting case! I wanted to post it here to see what people thought of it.

I think for more details you should speak to a certain Mr E at the Liverpool reference lab...

He was very excited too (they had a B el at the same time which was great for comparison & also very unusual!)

I had thought about the Lewis type also but with the patient being pregnant they didn't do this (I think I would have anyway though). The sample is indeed on it's way (last night) to IBGRL & no I don't know the answer yet!

[Malcolm Needs ☆]

Hi Malcolm, indeed this is an interesting case! I wanted to post it here to see what people thought of it.

I think for more details you should speak to a certain Mr E at the Liverpool reference lab...

He was very excited too (they had a B el at the same time which was great for comparison & also very unusual!)

I had thought about the Lewis type also but with the patient being pregnant they didn't do this (I think I would have anyway though). The sample is indeed on it's way (last night) to IBGRL & no I don't know the answer yet!

Thanks Fluffy.

I'm off until Monday, but will certainly talk to "The Egg" on my return.

I await Joyce's findings with a great deal of interest.

When she gives her verdict, will you post the result please?

:confused:

[Fluffy agglutinates]

I certainly will.

Enjoy your time off!

[Malcolm Needs ☆]

Thanks Fluffy, but I'm actually off on certified sickness leave; I'm a poorly boy!

[Fluffy agglutinates]

Well in that case I wish you a speedy recovery & best wishes!

[Fluffy agglutinates]

Possibly stupid question: could the failure to absorb and elute be from having too little antigen and insufficiently avid antibody? It sounds like she must have some tiny amount of B substance that prevents her from making anti-B.

Maybe some molecular testing or genetic testing could help.

A family study would be interesting.

Hi, definitely not a stupid question. In theory I suppose it could happen. The anti-B used was very avid though!

[adiescast]

I guess one thing I wondered is whether the anti-B used was human source. That might react differently than murine monoclonal source antibody in absorption/elution studies.

[Malcolm Needs ☆]

I guess one thing I wondered is whether the anti-B used was human source. That might react differently than murine monoclonal source antibody in absorption/elution studies.

I agree entirely (why I asked the series of questions in my earlier post).

For one thing, if it is a genuine Bhm, it could be that any B antigen on the red cells comes from adsorption of small amounts of B substance from the plasma (Type I chains), rather than being an integral part of the red cell membrane (Type II chains). Murine monoclonal antibody may not "recognize" these Type I chains as well as it does Type II chains, and these Type II chains are more easily "washed off" during the initial washing stages of the elution (depending on what elution technique was used.

:confused:

[Yanxia]

I have read the posts before mine, they are so brilliant.

I have encountered a parabombay type luckyly, the cells not react with anti-H and have B antigen weakly but can agglutinated with anti-B directly not use adsorption & elution test. I know there maybe some different between two parabombay.

We use human sourse antibodies to detect subgroup in 22 and 4 degree C with O cells be negative control, and use heat elution for ABO antigen and antibodies detection( 56 degree C 10 min elute , elution fluid test in 4 degree C 1 hour or past night with corresponding cells and O cells as neg control)

And I think the positive and negative control is very important, for example, anti-H we use 2 B cells and 2 O cells, adsorption and elution we will add one O cells tube be negative control .

Edited December 12, 2009 by shily

[yolis76]

Any results for this case?

[TimOz]

I agree with Shily. This pattern can be seen with parabombay. Illogical results may be reagent sensitivity issues rather than a true H negative phenotype. Le typing may be useful, even though pregnant. I await Joyce's findings.

[Fluffy agglutinates]

Still waiting for the report to come back!

[L106]

Very interesting case. Thank you for sharing it, Fluffy agglutinates. Made me brush-up on the B subgroups (which seem to be extremely rare in our non-urban areas of the US.)

[Fluffy agglutinates]

Ok folks an update for you...

IBGRL results are in: patient is a Bh, genetic background BO1

Antibodies: Strong anti-A, weak anti-B, but has not produced anti-H

Patient is of Cantonese ethnicity.

Baby due in about 4 weeks. No 28 week sample was sent in - so developing antibodies have not been checked of late.

What blood would you like on standby at delivery for Mum?!

[Malcolm Needs ☆]

Ok folks an update for you...

IBGRL results are in: patient is a Bh, genetic background BO1

Antibodies: Strong anti-A, weak anti-B, but has not produced anti-H

Patient is of Cantonese ethnicity.

Baby due in about 4 weeks. No 28 week sample was sent in - so developing antibodies have not been checked of late.

What blood would you like on standby at delivery for Mum?!

Ideally, blood of the same ABO group, or Oh, but these are very,very rare.

In this case, as there is no anti-H, I would want group O that is negative for high titre ABO antibodies.

I say this, knowing that such blood may stimulate an anti-H. This would, of course, cause problems if maternal transfusion is required later in life, but would not cause a big problem with another pregnncy.

:)

[Yanxia]

Thank you, Fluffy.

I want to know if the anti-B reactive in 37 degree C.

And thank you, Malcolm.

Can you explain why this lady transfuse group O cells stimulate an anti-H would not cause a big problem with another pregnancy, dose anti-H can't cause HDFN? Thank you again.

[Malcolm Needs ☆]

.

And thank you, Malcolm.

Can you explain why this lady transfuse group O cells stimulate an anti-H would not cause a big problem with another pregnancy, dose anti-H can't cause HDFN? Thank you again.

It is not actually the maternal anti-H that is the parameter to look at here, but the "strength of the H antigen on the red cells of the foetus/newborn baby.

Although the H antigen is in a completely different Blood Group System to the ABO antigens, both systems are governed by the kinetics of the transferase enzymes leading to the "insertion" of the immunodominant sugar residue on the various "backbone" molecules.

Like the alpha-1-3-N-acetyl-D-galactosaminyl transferase in a group A baby, and the alpha-1-3-galactosyl transferase in a group B baby, the alpha-1-2-fucosyl transferase in a group H (group O) baby is not working to its full capacity at birth, and some of the H antigen, like the A and B antigens, are histoantigens, "mopping-up" much of any maternal anti-H that may cross the placenta.

Of course, I am not saying that anti-H cannot cause HDFN, all I am saying is that, usually, it would be of subclinical significance (like the vast majority of maternal antibodies against the A and B antigens).

I hope I've explained that okay and in a logical fashion.

:D:D:D:D

[Fluffy agglutinates]

Thank you, Fluffy.

I want to know if the anti-B reactive in 37 degree C.

I don't know if they did any tests at 37 but I would think it unlikely as the original reference lab couldn't detect the anti-B at room temp or 4oC.