We have an  obstetric patient who is group AB CCDee, DAT neg and has an anti-c.The anti-c was reactive in the reverse group of the ABO so we used A1 and B CCDee red cells to confirm the ABO and were surprised to see that the B cells were strongly positive. We have genotyped the patient and this confirmed that the patient is AB. We then investigated the sample for the presence of cold reacting antibodies however the panel was negative but the B cells  and auto were. positive(RT tube). We tested with a further 2 B CCDee and 1AB CCDee. The two group Bs were positive but the AB was negatve.(Rt tube)  It looked like an auto ant-B bit this doesn,t explain why the AB was negative but the auto was positive. Just thought I would ask if anyone has seen anything like this before or if anyone had an explanation? 

 

 

Interesting case.

 

I can't remember ever having seen this (or read about a similar case).

 

When you say "genotyped", do you mean at the molecular level?

Yes it was done using an ABO genotyping kit.  We have run out of sample now but have requested further samples to try and reproduce the results as we only had enough plasma to do one test v AB CCDee red cells.

My first thouth was anti BI (anti B only reactive with adult and not cord cells), but the non reactivity of the AB sample confuses me. That exclude anything directed against a B antigen.

 

Was anti Cw excluded, that can reactive at RT and CCDee are more often pos. Just an unlucky draw with the B cells.

 

It would be nice to hear about the follow-up.

 

Peter

Might consider steric hinderence with respect to the reaction of patient plasma with the donor AB cells as the molecular structure of this antigen would differ from that of the patient who appears to be A-subB. Have you tried any other enhancements of this reaction?

Edited June 20, 201312 yr by rravkin@aol.com

Yes it was done using an ABO genotyping kit. We have run out of sample now but have requested further samples to try and reproduce the results as we only had enough plasma to do one test v AB CCDee red cells.

If you are right with the auto-B Ab. AB cell shoud give the positive result with the plasma (Am I right?).

If you are right with the AB blood group genotipicaly, This group may be cis AB with anti-B (if anti-B's rxn is 1+ (reverse grouping) )

Edited June 21, 201312 yr by zafer

If you are right with the auto-B Ab. AB cell shoud give the positive result with the plasma (Am I right?).

If you are right with the AB blood group genotipicaly, This group may be cis AB with anti-B (if anti-B's rxn is 1+ (reverse grouping) )

What is the strength of auto and with the two B CCDee tubes?

I have found the A antigens on the AB cells reaction is half strength of the group A1 cells, so does the B antigens.

Try to add more plasma or prolong the incubation time or at 4 degree C may enhance the  weak reaction .