Hey all, 

I was wondering how you all QC your Anti-A1 lectin, particularly if you use commercial A2 red cells as your negative control. Background: We do not QC Anti-A1 lectin daily only as needed, we use commercial A1 red cells as our pos control, A2 as our neg.  However, we then QC our A2 cells (bc they are not included in the QC of our daily rack QC) which I find to be unneccesary and wasteful.  Why would you QC your QC? You are accessing the functionality of Anti-A1 not the A2 cells, right? Why not just use B cells if they have to be QC'd. Just curious if I am missing something.  I am really wanting to get rid of this practice if possible, and I am currently going through CAP and AABB standards for clarity.

Thanks  

I attach a hybrid of my lectures on the differences between the A1 and the A2 ABO type, together with a very few slides from my lecture on lectins, and I hope that this will serve to be of some use to you.

It is hugely important to remember that many lectins, including Dolichos biflorus, are not specific unless they are diluted to ensure that they only react as desired.  For example, this particular lectin (Dol b) will react quite strongly with A2 red cells unless suitably diluted so that it only reacts with A1 red cells.  It is because of this that group B red cells are totally unsuitable to be used as the negative control for the Dol b lectin, and the same applies for group O and other group A subtypes.  Group B red cells will not tell you whether or not your grouping reagent is "specific" for the A1 antigen, or will still react with the A2 antigen.  In addition, the lectin will also react with red cells expressing the rare polyagglutination antigens Cad and Tn, and so, in the true meaning of the word, it is not "specific" anyway.

What is the difference between A1 and A2.pptx

On 9/18/2021 at 4:26 AM, Malcolm Needs said:

I attach a hybrid of my lectures on the differences between the A1 and the A2 ABO type, together with a very few slides from my lecture on lectins, and I hope that this will serve to be of some use to you.

It is hugely important to remember that many lectins, including Dolichos biflorus, are not specific unless they are diluted to ensure that they only react as desired.  For example, this particular lectin (Dol b) will react quite strongly with A2 red cells unless suitably diluted so that it only reacts with A1 red cells.  It is because of this that group B red cells are totally unsuitable to be used as the negative control for the Dol b lectin, and the same applies for group O and other group A subtypes.  Group B red cells will not tell you whether or not your grouping reagent is "specific" for the A1 antigen, or will still react with the A2 antigen.  In addition, the lectin will also react with red cells expressing the rare polyagglutination antigens Cad and Tn, and so, in the true meaning of the word, it is not "specific" anyway.

What is the difference between A1 and A2.pptx 512.68 kB · 2 downloads

Thanks Malcom! I know A1 lectins need to be diluted properly but didn’t think it all the way through to that’s why A2 cells are a necessary negative control.