Autoadsorptions

[DCeDCe]

Hi,

My Blood Bank is currently looking to perform autoadsorptions for our patients with warm autoantibodies, as we get quite a few and spend a lot of money sending them out to the reference lab. We recently purchased Immucor’s W.A.R.M. reagent, and we are attempting to validate it. We are comparing our results to what the reference lab reports out to us, but we are running into discrepancies. The last 2 patients that we sent to them, were reported to us as warm reactive autoantibodies present with no underlying allo antibodies. However when we performed absorption’s to compare, our panels showed what looked like antibodies with specificities, after the autoantibody was adsorbed out (one fit a little e pattern, and one looked like an anti-D). Since our results do not correlate with the reference lab results, I called them to find out what they treat their cells with. They said they make a home brew of papain and DTT together. The immucor W.A.R.M. that we used, according to the package insert says that it is lypholized papain and DTT , which is the same. I don’t understand why we would get such discrepant results? If anyone out there has some answers I would totally appreciate it!! How can we move forward with our validation if our results never match? Please help!! 🙂

[Malcolm Needs ☆]

Hi DCeDCe (great name - all the best people have that as a probable Rh genotype!),

The thing to remember is that warm autoantibodies tend to be mimicking antibodies.  It is probable, therefore, particularly as you are both using ZZAP, that the Reference Laboratory is either doing more rounds of adsorption than are you with your W.A.R.M. reagent, or that, as they are making up their own ZZAP reagent, there is a resultant difference in how many autoantigens are exposed after the partial removal of the sialic acid residues.

Either of these explanations could result in the Reference Laboratory removing more of the autoantibody than are you; in other words, they are removing all of the autoantibody, while you are removing most of the autoantibody, but not all, and under these circumstances it is much easier to see the "false" specificity of the autoantibody.

To show matching results, it could be something as simple as you doing a further adsorption with your W.A.R.M. reagent treated red cells.  Put it this way, it might be worth a try!

Incidentally, "cold" autoantibodies tend to have a true specificity.

[exlimey]

I agree with Malcolm - all the best people are DCeDCe.☺ I also agree with his analysis. The differences you are seeing are probably because you are not doing as complete an adsorption as the IRL. Indeed, this partial and sequential adsorption process was the heart of the early work by Dr. Issitt (and others) when they were trying to determine the specificities of autos.

Most warm autoantibodies mimic Rh specificities (there are exceptions). The older literature is full of anti-e-like autos and antibodies to compound antigens (Ce, cE, etc.). There are also a smattering of anti-D-like autos. Not uncommon, by any means. Some labs used to make an effort to ID autos, but in recent years, time and money have have almost eliminated this potentially interesting technical challenge.

 

[David Saikin]

Have you tried the PeG autoabsorption?  I have used this since first reading the article in Transfusion in 1999.  It is easy and fast.  Only one time has it failed to absorb all the autoab. (I tried 4 absorptions/my referral facility tried 8 - neither of us had a complete absorption). 

[DIANITA]

Do you have a procedure you could share

[David Saikin]

16 hours ago, DIANITA said:

Do you have a procedure you could share

there is one in the current Technical Manual

[DCeDCe]

David Saikin,

Can you perform a PeG adsorption using autologous cells? I thought the whole point of using ZZAP is to free up antigen binding sites on the cells that are currently bound with the autoantibody. How does PeG achieve this?