meeting p-values on Galileo ECHO

[mary h]

Just curious about what everyone is doing to meet the p-values when performing antibody indentification on the ECHO. In tube, we have always accepted 3 reactive and 3 nonreactive cells to meet p-values. We just started performing antibody ID on the ECHO and the three panels available for automation do not always provide enough cells to get 3 reactive. Some of the antibodies detected on the ECHO were not detected in our tube method using PEG. Any thoughts?

[Sherry Quintey]

Mary,

We still follow the 3 rule on the ECHO for newly identified antibodies. Occasionally we will have to run a couple of cells manually (we also use PeG) to complete the ruleouts or confirmation. We have found that the Ready Id works well for most antibodies. If it is a previously identified antibody, we only require 1 cell so we know if it is still expressing.

[hmust1]

With any manufactured panel, you might encounter a situation where you don't have the right combination of antigens to rule in/out every possible antibody. Additionally, antibody identification policies may differ from institution to institution. If your facility actually has a policy that says you need to use 3 reactive and 3 nonreactive cells per antibody, I'd personally consider that overkill. I've worked at both large facilites (that only rule out antibodies based on one heterozygous antigen expression alone) and small facilities (that religiously follow a 3 hetero/1 **** rule, regardless of how many seleted cells they have to run). Personally, I think that somewhere in between is still quite a safe alternative for the patient. Remember, you always have the AHG crossmatch to fall back on.

We've used our Echo for antibody identification for almost 3 years now and I've never felt like the automated panels have left us completely in the dark. I require 1 homozygous or 3 heterzygous rule outs on the major antibody classes and fewer for the low frequency antibodies depending on the pattern of reactivity. On a rare occasion, depending on the antibody (or combination thereof), we do resort to pulling out the tube panel and running a few selected cells. Frankly, this just 'makes us feel good.' The sensitivity of the two methods is SO far apart. Even heterozygous cells will react stronger on the Echo than homozygous cells will react in tube...in my experience.

Also keep in mind, that there is no requirement (that I'm aware of) from AABB to meet a certain 'p-value' when ruling in/out antibodies. In fact, with regard to known antibodies, the AABB technical manual specifically says that it is not necessary to test antigen positive cells to re-confirm previously identified antibodies. So, that alone might greatly cut down the number of circumstances that you feel you need to have the '3 reactive cells.'

Just some ideas...hope this helps.

[mary h]

Our biggest concern was "ruling in" new antibodies. Of course we would honor an antibody if we could not rule it out, but we were curious as to if we needed to change our antibody ID procedure. Since we are new to automation, we wanted to see what the "pros" :)were doing. I appreciate the responses.

[Sherry Quintey]

Yes, it is not necessary to reconfirm previously identified antibodies, but we run 1 positive cell to see if it is still reacting. If it is not reacting we put a comment in the patient's history so the next time we see the patient, we start with a Type & screen. We are a community hospital that has generalists covering the Blood Bank on evening and night shifts. This is to give them some direction. That way they can proceed with antigen typing units for the crossmatch.