We have one unit of group O positive blood that we unexpectedly got a 4+agglutination by tube and a 2+ agglutination by gel card when we crossmatched to a patient with a negative antibody screen. We did a polyspecific DAT and a monospecific DAT by gel card and both were negative. Group and antibody screen of the donor was checked and was confirmed O positive with negative screen. We then crossmatched the unit with five random patients of different groups who all had a negative antibody screen.  The unit was incompatible with all five patients. What could be the reason for this one unit being incompatible with supposedly different "normal" patients? I feel I am missing something obvious here? Should we send the unit for culture?

I think it more likely that the donor is expressing an antigen, such as T, Tn, Tk, Cad, etc, possibly as the result of a subclinical infection if this has not been seen before with his/her blood (which would rule out Cad).  Have you tried testing it with a lectin panel?

I would suggest running a select panel of low-frequency antigens against your patient's plasma (V, Cw, Jsa, Kpa, LUa, Bga, Ch, etc). If the patient has one of those antibodies, the antibody screen would still be negative and, likely, so would your panel if there is no positive cell included. The unit may have the corresponding antigen. I have seen this several times. Since we don't routinely do serological crossmatches in the presence of a negative antibody screen, these antibodies are normally not found until a transfusion reaction investigation.

3 hours ago, Malcolm Needs said:

I think it more likely that the donor is expressing an antigen, such as T, Tn, Tk, Cad, etc, possibly as the result of a subclinical infection if this has not been seen before with his/her blood (which would rule out Cad).  Have you tried testing it with a lectin panel?

We have never used a lectin panel before. Are these commercially available?

29 minutes ago, YorkshireExile said:

We have never used a lectin panel before. Are these commercially available?

They always used to be, but having retired in October 2016, I am no longer sure that they are.  Anyone else know?

I would pull the unit from inventory and contact the supplier. They should have the resources to investigate the problem with the donor.

2 hours ago, jayinsat said:

I would suggest running a select panel of low-frequency antigens against your patient's plasma (V, Cw, Jsa, Kpa, LUa, Bga, Ch, etc). If the patient has one of those antibodies, the antibody screen would still be negative and, likely, so would your panel if there is no positive cell included. The unit may have the corresponding antigen. I have seen this several times. Since we don't routinely do serological crossmatches in the presence of a negative antibody screen, these antibodies are normally not found until a transfusion reaction investigation.

This scenario doesn't explain why the donor red cells react with the serum from most patients. For this to be a "low incidence antigen" issue, ALL of the patients would have to have an antibody to (probably) the same low incidence antigen. That is very unlikely. As Malcolm suggests, this sounds like an abnormality of the donor's red cells.

I believe Hemo bioscience have a lectin kit, but it may only be available in the USA.

Could the unit be a weak A or B?  How was its ABO performed and confirmed?    Try crossmatching with an A and B patient if you don’t have a lot of different reagents. 

20 hours ago, exlimey said:

This scenario doesn't explain why the donor red cells react with the serum from most patients. For this to be a "low incidence antigen" issue, ALL of the patients would have to have an antibody to (probably) the same low incidence antigen. That is very unlikely. As Malcolm suggests, this sounds like an abnormality of the donor's red cells.

I believe Hemo bioscience have a lectin kit, but it may only be available in the USA.

Yes. I missed that part about it being crossmatch incomplatible to other normal donors. 

I would definitely return the unit to the supplier.

Thank you all for your suggestions and helpful information.  Unit has been returned to supplier as there is no way we could use it for any patient.  Investigations are underway....

Edited July 23, 20204 yr by YorkshireExile

As someone that works in a small blood collection facility, my first thought was how did this get through testing. Then I realized the problem is probably related to the antigens, not an antibody. First thing we check is DAT of the unit, which is negative. Then we would test against a couple of random samples from each compatible blood type, which you did. Then I would do a more elaborate ABO, which if there was a problem should have (in theory) been caught during testing. Then I thought about your reactions, 4+ tube, 2+ Gel, that's backwards from "normal" reactivity. Here we see a difference in reactions of at least one, usually two levels higher in Gel than tube. Unless whatever is happening is more IgM than IgG....... Then I think, do we all have Nabs that would react to some super low-incidence antigen? That was literally my thought process in 2 minutes, with no logical brakes. LOL. I'm not knowledgeable enough with this off the top of my head, so now it's time to read. Please post what the supplier says.  

Edited July 23, 20204 yr by sbraden

When I was at the Red Cross Reference Lab, we once had a donor who had donated 13 times as an O NEG.....then was determined by the regional donor testing lab to be a very weak subgroup of A (not sure of all of the testing they had performed to detect this and why it would not have been detected before this....but it was confirmed). Someone above suggested perhaps a weak A (or B subgroup)......maybe there is something to that??  Were all of the patients you tested against this unit, group O?

Just a thought

Brenda Hutson

What about reverse grouping? If forward and reverse grouping and quick ab screening (at RT) are ok, Malcolm's opinion gains importance.

Zafer CINAR