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Davidwa

Questions about allo absorption

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I am trying to introduce allo absorption technique to our blood bank, due to high incidences of WAA patients with chronic transfusion dependence. Currently we have to send all these recently transfused patient samples with WAA to reference lab. Now we are exploring the possibility to do allo absorption in house. I am not sure how far we can go, really. But I hope we can accomplish it if I can get help and support from your guys with plenty of experience on allo absorption.

1. The top challenge is how to get donor cells with R1R1, R2R2, rr with combination of Kell, Kidds, Duffy positive/negative cells. If you find a donor unit meeting your requirements, how did you get the pack cell (say 5 ml or 10 ml) from the main unit bag? Cut segments? or draw the cells from the main bag then seal it?

2. if draw cells from the main bag, how many days for the main bag valid for future testing ? the original expiration date or does not matter since it was not meant to for patient transfusion?

3. or can we subdivide the whole bag into multiple small tubes or transfer bag? how to store these aliquots? expiration date?

4. any reference (literature and websites) and SOP can share? 

5. Triple absorption is least I want to perform if I have patient phenotype or genotype information. That will make easier to do allo absorption. Some people said geno type should not be treated as phenotype unless phenotype confirmation performed. Not sure this is main school of thoughts or not. 

6. Finally, is there any company providing commercial triple absorption cells in the market? Panel cells not feasible to do absorption right?

Any help for any above question highly appreciated. 

   

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We used to sacrifice the whole unit and freeze aliquots of treated units.  We now do so many we can leave them resuspended I believe in Alsevers.  In the long ago past we would take off a small aliquot and treat that and use the rest of the unit.  It was a tremendous amount of stress finding the units, treating them, then testing the patient.  It would take almost 2 full shifts.  Lot's of staff stress and also delays for patients.  Have the frozen cells was great, now having them liquid is even better.

It's a balance.  If you do enough, you can consider having cells available, if not, it may be cheaper and less stressful to keep sending it out.

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And don't forget that you will have to maintain competencies. You will probably have to send out some split samples to your reference lab or find some other means of proving that your methodology and process are good for regulatory purposes. I stopped doing even autoadsorptions because it just got too complicated and spendy to deal with those kinds of issues. Not saying don't do it, just keep an eye on the details.

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I agree with Cliff and AMcCord. I suggest to first determine if your lab can afford the time, i.e. do you have enough techs to work-up warm autos that require allo adsorptions in addition to your current work load. If you can and do then look for the answers to your list. 

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Maybe you can identify 3 employees who meet the typing criteria willing to give you blood when you need it.  Might be some regulatory hurdles to that nowadays though.

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Most people would sacrifice the entire unit to perform allo-adsorption. In this case, most hospital blood bank would not be able to use up the entire unit fast enough so will be wasting some the adsorbing cells, if not kept frozen (as most hospital do not have a nitrogen tank or ultra low freezer). The other option to use donor unit is to gluderaldehyde-treat and freeze the stroma for later use. 

The other more feasible option is to type the lab (or blood bank) employees (of course with their consent) to have them as donors for adsorbing cells. When you have to perform adsorption you can use your staff's red cells as adsorbing cells. In this case, it will be an adsorption using the phenotype similar cells with your patient rather than a differential adsorption using 3 cells. 

 

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1. In the book Judd's Methods in Immunohematology, auto adsorption is not feasible if pt transfused in 120 days. but in AABB tech manual method, the cut off is 3 months, i.e., 90 days. Would 90 days acceptable for auto adsorption? or have to stick to 120 days? any input?

2. AABB method implied that the typing on patient's reticulocytes by harvesting autologous red cells should be exercised with caution for interpretation of the E, e, c, Fya, Jka, and Ge antigens. How can be confident to the typing results for those antigens just mentioned? If no confidence, this method is not valuable to type the pt recently transfused. The reason I asked is that I eagerly to find ways to use pt typing information to assist allo adsorption. 

3. I can use genotyping information, but it will take 2-3 days to get results and we may not wait so long in some cases. 

 

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