Preparing Teaching Samples for ABO Discrepancy

[KKidd]

In a few weeks I will begin training a new MLT with no experience. Does anyone have a method of preparing samples to yeild ABO discrepancies? I am saving samples on patients with known antibodies. Thanks!

[Malcolm Needs ☆]

One thing that you could do is add group O red cells to group A or B red cells, wash them, and resuspend them in inert AB plasma/serum to mimic a chimera or the kind of reactions that you get soon after a stem cell transplant.

 

Another is to add washed group O red cells to group A or B red cells to mimic the kind of reactions that you would find after an ABO non-identical transfusion.  If you judge this one well, and you add washed group O red cells to group A2 red cells, you will get mixed-field reactions that mimic an A3 (and, if you add some Dolichos biflorus, then it can mimic an A3 with an anti-A1).

 

Use washed A, B or O red cells, resuspended in inert AB plasma/serum to mimic cord blood (as long as your students are not clever enough to test the red cells with an anti-I)!!!!!

 

That's a few to be going on with.  I'll keep thinking.

[tbostock]

Acquired B: Take an A patient, add some B reagent cells to it so that your A front type is 4+ but the B is very weak (1-2+).

[Malcolm Needs ☆]

The only problem with that Terri is that the "patient's" own anti-B will agglutinate the group B cells that you add.  If you first wash the group A and group B cells, and then resuspend them in AB plasma/serum, this will not mimic an acquired-B phenotype, as such individuals do have an anti-B in their plasma/serum, but this anti-B does not react with their own red cells or any other red cells from the same sort of acquired-B (but does with other sorts of acquired-.

 

On the other hand, of course, if you give the candidates samples that have already been separated, this would work well (unless they run an auto).

 

If you give the candidates samples that have already been separated, there is all sorts of tricks that you can get up to in order to mimic wierd and wonderful ABO types!!!!!!!!!!

[Dr. Pepper]

I do these with my students and trainees. Having the good fortune to have a real problem patient on hand is great, but you can make these up yourself:

 

1. Weak antibodies - titer the serum of a group O, A or B and test at 4oC. Find the dilution that reacts 1+ after incubation at 4oC and ensure that that dilution will not cause agglutination at RT immediate spin. Use that dilution as your serum for the problem patient. Your MLT will have to do a cold backtype.

 

2. A2B w/ anti-A1: Dilute some anti-A1 1:2 or 1:3 to use as the serum and A2B (or a mix of A2 and cells for the front type. I like to make the problem patient A2B rather than just A2 (in which case I would add a few drops of reagent anti-B into the serum mix) to remind them that A and B subgroups can pop up in AB patients as well.

 

3. If you have a nice IgM antibody, patient or reagent, that reacts with the back type cells, great. Otherwise, reagent anti-c diluted 1:2 will usually react well with your A and B cells in the backtype. You can point out an Rh antibody would not usually react like that, but the principle of doing an I.S. antibody screen and panel to find an unexpected antibody mucking up the backtype remains the same.

 

4. Adsorption/elution test for weak A or B antigens. I start off with the newbie doing a bunch of routine typings on old saved specimens (hematology or coag "just in case" tubes from the ED from a few days past, about to be discarded) and hence finding several A (or and O specimens. You can make your "weak A" by mixing 1 part A cells with 9 parts O cells - this will work like a champ in the procedure. Start off with paper reactions showing what led you to this point: apparent O on front type, apparent A or B on backtype, but couldn't get the expected A or B cells to react with a cold back type.

Edited July 24, 2013 by Cliff
Fixed emoticons

[Dr. Pepper]

Malcolm, I shouldn't have made fun of your killer bees the other day. Look what this did to my B followed by )!

[Cliff]

Malcolm, I shouldn't have made fun of your killer bees the other day. Look what this did to my B followed by )!

 

I fixed it for you, you needed to unselect "Enable emoticons?" otherwise the site processes it into a smilie face.