Making ABO discrepancies for teaching

[Mabel Adams]

The Tech Manual says to use saliva from known secretors and non-secretors as controls. It also lists under "Reagents", "Human (polyclonal) anti-A and anti-B. Note: some monoclonal reagents may not be appropriate for use, therefore, apprpriate controls are essential." Saline is also run. The anti-A used is diluted till it produces a 2+ agglutination.

For testing the A substance only, I would have 4 tubes: 1) known secretor's saliva +Anti-A, 2) known non-secretor's saliva + anti-A, 3) saliva being tested + anti-A, & 4) saline + anti-A. After these incubate, A1 cells are added to each tube to see if the A substance in the saliva neutralized the diluted anti-A.

Now that I have thought it through, only the non-secretors would produce agglutination so in a way that is actually the positive control--at least in my brain.

[galvania]

I make a stable anti-A1 by absorbing an anti-A from an O donor with A2 cells. I then give the students A2 cells and my absorbed anti-A (which still has anti-A1 activity) in separate tubes

As for making a weak D - I can't! Definitely no use mixing D+ and D- cella - you just get a definite double population if using gel

[rcurrie]

Anna, I agree that you can't "make" a weak D. Luckily for me I now have a regular weak D donor, and he allows me to collect an extra tube for my students. Until that happened, I would make two "weak D" patients. For one I would use 2 drops R2R2 plus 18 drops rr, and for the other I would use 2 drops CCC plus 18-24 drops rr. The purpose of my weak D exercise was for the student to tell me which specimen was a possible weak D and which specimen was probably not weak D due to the positive DAT. I would explain that this isn't what a true weak D looks like but that the point was to do a DAT, and if it was positive, then probably not weak D. Now I have that weak D donor source. I also have a donor who is A2 making anti-A1. I have about a gallon of his plasma frozen in single tube aliquots. Bring on the students!

BC

[ckcheng]

To make anti-A1, try this recipe: Adsorb group B patient plasma with A2 cells.

Hope this helps.

CK Cheng, MSc, SBB(ASCP), CQA(ASQ)

Hong Kong

Dec 3, 2008

[Yanxia]

Ckcheng mentioned a good method to make anti-A1. Do adsorb we need pay attension not excessive, because this can adsorb anti-A1, too.