A subgroup donor w/ Anti-A1

[jhodam]

Hello,

We have a regular donor that is a subgroup of A, most likely Ax or A3. Their red cells fail to react with reagent Anti-A or Anti-A,B. The donor also has anti-A1 that reacts 3+ in the reverse type, so taken together reactions are consistent with a type O donor. The only reason we know the units type is that our local community blood bank tags it with a “heads up†card (as they like to call it).

Since we are unable to confirm the type of the donor when we receive the unit from the collection facility, I am wondering if we are out of compliance with the requirement for confirmatory testing of donor blood? Or is the report from the reference typing lab good enough with Medical Director approval?

I am also curious about how this might have been discovered in the first place with this donor, as he/she types straight up O pos. I can coax the forward type out with Anti-A,B in the fridge for 10 minutes, but it’s barely macroscopic, and such a procedure wouldn’t be standard practice for the reference lab doing the typing the first time this donor was tested. They do their types on a Galileo, the same as we run ours on, so I know they aren’t using a different method or different reagent. What are the chances a donor like this could be missed in general and have their blood end up in a O patient?

Thanks in advance,

Jason

[keisterkid]

It is probably missed more than we BBers would like to admit. In our reference lab when ABO discrepancies are referred to us we use A1, A2 and B cells for the reverse typing. If we can't bring up an anti-A with the A2 cells we call the donor an ABO discrepancy. When requested we will perform adsorption/elution studies to prove the ABO type, but the product isn't labelled since the client that receives the product won't want to take the time and expense to duplicate our work to confirm the ABO.

[L106]

It is probably missed more than we BBers would like to admit. In our reference lab when ABO discrepancies are referred to us we use A1, A2 and B cells for the reverse typing. If we can't bring up an anti-A with the A2 cells we call the donor an ABO discrepancy. When requested we will perform adsorption/elution studies to prove the ABO type, but the product isn't labelled since the client that receives the product won't want to take the time and expense to duplicate our work to confirm the ABO.

We're talking a donor that is a subgroup, right? Would most donor centers even bother to dispense this donor unit to a hospital? (Of course you shouldn't transfuse the donor unit to a Group O patient, but you also would't want to give it to a Group A patient, since the donor unit has Anti-A1.)

[keisterkid]

We're talking a donor that is a subgroup, right? Would most donor centers even bother to dispense this donor unit to a hospital? (Of course you shouldn't transfuse the donor unit to a Group O patient, but you also would't want to give it to a Group A patient, since the donor unit has Anti-A1.)

1. We are talking about a donor and calling it an ABO discrepancy means, to us, that the unit is not distributed.

2. We do transfuse A units to patients with anti-A1 after proving that the antibody is clinically insignificant.

[jhodam]

1. We are talking about a donor and calling it an ABO discrepancy means, to us, that the unit is not distributed.

2. We do transfuse A units to patients with anti-A1 after proving that the antibody is clinically insignificant.

Just for discussions sake, would anti-A1 in this unit, if clinically significant, be of more concern than IgG anti-A1 in an O unit of red cells? Or for that matter a unit of O platelets going to an A or B recipient? We check for high titer anti-A and B in platelets and transfuse O's to A's if below 1:200, do other institutions with a similar policy look into immunoglobulin class as well before serologic mismatches are transfused?

Thanks,

Jason

[David Saikin]

Decades ago, prior to monoclonal reagents, we had a donor we typed as a group B. Front typed as a B and back typed as a B. We were trying out some monoclonals and just happened to have this donor recently drawn. Front typed as an AB, with the reaction with anti-A 1+. Turns out the donor was actually a weak subgroup of A/B with anti-A1. Tracking the original donation, we found that it was transfused to a group B individual. There was no evidence that the transfused cells did not survive normally. We did file an error report with the FDA, but, there were no repercussions as all procedures were performed correctly. This was just one of those types that presented the way human derived reagents reacted at the time. Subsequent donations were tested with monoclonals, and we transfused as a group AB. The anti-A1 was not clinically significant for our transfusion purposes, esp as an additive solution red blood cell. There were no plasma components/platelets made from these donations. That's why they call it practicing Medicine.

[noelrbrown]

In my experience in a donor center we would ALWAYS check new group B donors with A2 cells to make sure they had an anti A and not just anti A1 i.e. were not a A3B etc. I am surprised the initial post indicated the A3 or Ax could not be detected with monoclonal anti A as this is part of acceptance testing for these reagents. Its also a good idea to check your anti AB that you use, some are a true anti AB clone and others are simply a blend of Anti A and Anti B.

[Malcolm Needs ☆]

In my experience in a donor center we would ALWAYS check new group B donors with A2 cells to make sure they had an anti A and not just anti A1 i.e. were not a A3B etc. I am surprised the initial post indicated the A3 or Ax could not be detected with monoclonal anti A as this is part of acceptance testing for these reagents. Its also a good idea to check your anti AB that you use, some are a true anti AB clone and others are simply a blend of Anti A and Anti B.

I agree; the donor is much more likely to be an Am, an Aend or something like that (much weaker than an A3 or true Ax).

AS for how the donor was originally found to be a subgroup of A, they may be using the same reagents by the same technology as you now Jason, but was this so when they first detected the A antigen on the donor's red cells? In any case, in such a situation, a Testing Department worth their salt should pass over any suspected ABO descrepancy (even if it turns out not to be so) to their own Reference Laboratory so that it can be checked with extra reagents, extra techniques (adsorption and elution, as suggested), different temperatures of incubation, and may even test saliva for the presence of A substance (although it is exceedingly rare so to do in this day and age).