Clinically insignificant antibodies

[javvcr]

hello everybody!

here is a question killing me this days!

what do you do when a M, N, P1, Le (a), Le ( or Lu (a) does appear in the antibody screening before transfusion requierment?

Edited August 1, 2009 by javvcr

[Lcsmrz]

Once we confirm that an antibody is clinically insigificant, we usually prewarm it away and give crossmatch compatible blood.

Antibodies like Cw, Lu(a), etc, we give gel crossmatch compatible units.

[Malcolm Needs ☆]

hello everybody!

here is a question killing me this days!

what do you do when a M, N, P1, Le (a), Le ( or Lu (a) does appear in the antibody screening before transfusion requierment?

We too would give cross-match compatible random units.

We are a little more careful with anti-M, in that we will make certain that it does not react at 37oC.

I was on-call about a month ago and had to deal with a patient with a pan-agglutinating auto-antibody and known underlying alloantibodies. Having performed multiple differential alloadsorptions, there were still some extremely strong reactions that did not pattern for the known antibodies.

After a couple of hours, and much scratching of the head, I was bale to prove this to have a specificity of anti-M. It was amazing. It reacted 4+ in pre-warmed, warm-washed LISS tube IAT, using a monospecific anti-IgG reagent and, in my opinion, would have been very clinically significant. I've never seen an anti-M like it before.

In this particular case I made sure that the units were M-. I wasn't prepared to do an in vivo cross-match on that little blighter!!!!!!!!!!!!!!

[Malcolm Needs ☆]

I forgot to say, there are circumstances when we would not give compatible blood, but would give suitable blood.

These cases include such specificities as anti-Ch, anti-Rg, anti-Kna, anti-McCa, etc, but we would make absolutely certain that there were no detectable clinically-significant atypical alloantibodies lurking underneath.

On other occasions, where the antibody is known to be clinically significant, but where the antigen is of very low incidence within our population (I am thinking of anti-Wra, anti-Dia, etc) we would also give cross-match compatible, rather than typed antigen negative blood.

There, that's got that off my chest!

:D

[eric1980]

Malcom, I do not understand the difference between "compatible" and "suitable".

Could you explain more?

[Malcolm Needs ☆]

Malcom, I do not understand the difference between "compatible" and "suitable".

Could you explain more?

Yes, it can be a bit obscure.

Basically, what it means is that, if we cross-match using the raw plasma and we detect no reactions, or we cross-match using auto-adsorbed plasma, and we detect no reactions, then the blood is issued as "compatible with".

If we cross-match using the raw plasma, in which we have detected a clinically insignificant antibody, such as anti-Kna, we cannot provide Kn(a-) blood, as so we will cross-match and choose the least incompatible, and issue it as "suitable for".

If we cross-match using inhibited plasma, as in the case of anti-Ch or anti-Rg, we will also issue as "suitable for".

If we cross-match using alloadsorbed plasma, and we detect no reactions, we issue the blood as "suitable for".

The difference between the autoadsorbed plasma and the alloadsorbed plasma is that autoadsorption will leave behind an alloantibody directed against a high frequency antigen (such as an anti-Vel) - hence the "compatible with", whilst the alloadsorption will almost certainly take out an antibody directed against a high frequency antigen (again, such as anti-Vel) - hence the "suitable for".

To put it another way, if we issue blood as "compatible with", we are pretty sure that there will be no adverse reactions, whereas if we issue blood as "suitable for" we are hoping that there will be no adverse reactions (but it is still, to a certain extent, an in vivo cross-match).

I hope that helps to explain the difference. If not, get back to me.

:)

[Bill]

Along this line, does anybody have a list of what you give antigen negative units vs just gel crossmatch compatible units? If so, would you please post it here. This would be a great help to us smaller labs that do not have SBB's on staff. THANKs in advance for any jelp.

[RR1]

Hi Bill,

The document library on this site has the UK BCSH guidelines for compatibility testing that you can view. This guidelines contains the table we all use in the UK .

[eric1980]

Malcom, I've entered my own interpretation in italics and could you see if I have interpreted your post correctly? "Suitable for" is a new term to me and I am interested in making sure. =Þ

Basically, what it means is that, if we cross-match using the raw plasma and we detect no reactions (As what we always do - ideally), or we cross-match using auto-adsorbed plasma, and we detect no reactions (negative reaction in the presence of possible high-frequency alloantibodies), then the blood is issued as "compatible with".

If we cross-match using the raw plasma, in which we have detected a clinically insignificant antibody, such as anti-Kna, we cannot provide Kn(a-) blood, as so we will cross-match and choose the least incompatible (incompatible - might cause transfusion reactions), and issue it as "suitable for".

If we cross-match using inhibited plasma (antibodies still there, but silenced), as in the case of anti-Ch or anti-Rg, we will also issue as "suitable for".

If we cross-match using alloadsorbed plasma, and we detect no reactions, we issue the blood as "suitable for" (because of possible false negatives? clinically significant alloantibodies may be removed prior to crossmatching).

The difference between the autoadsorbed plasma and the alloadsorbed plasma is that autoadsorption will leave behind an alloantibody directed against a high frequency antigen (such as an anti-Vel) - hence the "compatible with", whilst the alloadsorption will almost certainly take out an antibody directed against a high frequency antigen (again, such as anti-Vel) - hence the "suitable for".

I owe you 2 lattes as of now. ; )

Edited August 9, 2009 by eric1980

[Eagle Eye]

Any time we have non specific reaction and we rule out all clinically significant antibody we give gel crossmatch compatible.

[Malcolm Needs ☆]

Along this line, does anybody have a list of what you give antigen negative units vs just gel crossmatch compatible units? If so, would you please post it here. This would be a great help to us smaller labs that do not have SBB's on staff. THANKs in advance for any jelp.

Although it is now 7-years-old, and so some of the newer antibodies described are not quoted, you couldn't get a much better paper , in my opinion, than:

Daniels G, Poole J, de Silva M, Callaghan S, Smith N. The clinical significance of blood group antibodies. Trans Med 2002; 12: 287-295.

[Malcolm Needs ☆]

Malcom, I've entered my own interpretation in italics and could you see if I have interpreted your post correctly? "Suitable for" is a new term to me and I am interested in making sure. =Þ

I owe you 2 lattes as of now. ; )

Yes, absolutely right (although, any plasma containing, for example, anti-Kna, will have been "tested to death" for the presence of an underlying atypical alloantibodies directed against the major blood group antigens against a battery of Kn(a-) red cells, kept for reference work, so we are pretty sure that there will be no overt haemolytic transfusion reactions).

Thanks for the offer, but, if you don't mind, and don't think me too cheeky, I'll swap the teo lattes for a glass of red wine!!!!!!!!!!!!!!!!!!!!!

:D

[TimOz]

Question for Malcolm re the anti-M you saw (sorry for the delayed question - I have been too busy).

I was messing around with the DiaMed monospecific DAT cards as recently as yesterday. I was using them for an IAT method rather than a DAT and getting very useful results. The testing I was doing was sorting out in vitro activated complement from real IgG antibodies and they worked a treat.

I always wonder about the variability of antibody behaviour of antibodies of the same apparent specificity and class between patients and the habit we have of saying "if it is RT reactive only, it is IgM and if it is IgM, it is not clinically significant". These cards seemed to provide a simple way for less experienced operators to be sure there is no alloimmune anti-IgG rather than just non-red cell immune IgM. Have you tried these cards by IAT? I assume your case would light up the IgG column but I wonder if there is any IgM.

[Malcolm Needs ☆]

Hi Tim,

No, I had not even thought of trying your idea.

I think it is a quite excellent suggestion, and I will certainly try it out.

Thank you.

:D:D

[AMcCord]

For a list of which antigens are clinically significant (requiring antigen negative cells for transfusion) and which are not, check out the AABB Technical manual. In the 16th edition, chapter 16 covers the pertinent information on pages 493 - 496. John Judd's Methods in Immunohematology, 3rd ed , available through the AABB bookstore, also has a nice section on this topic on pages 304 - 308 (page 308 lists about every antibody problem you could be cursed with).

[TimOz]

Malcolm.

FYI - I was just using a standard 50uL 0.8% cells + 25uL of plasma with standard incubation time. Very celan reactions.

Note that I was trying to determine the cause of rubbish reactions with fresh serum from clot activator tubes and this in vitro activated complement can really get in the way. It will light up the C3c and C3d columns. If you see it, you can throw the serum into an edta tube for 60 seconds and it will not be seen. Also note that if your cells are in ID-Dil 2, the complement will be neutralised (as if it has edta in it). I think this should be bourne in mind if you are actually looking for complement with these cards. Suspend your cells in some other diluent or it will kill any complement reactivity - in my experience.

I also very heavily coated an RhD+ve cell with a monoclonal IgG anti-D and it all got messy. The control column lit up as did a few of the others. Using routine samples I found no problems and it was very useful.

Of course the other nice thing is that you can take very nice photo records. I have a pic of a very strong anti-Mur that I can show is pure IgG (as opposed to just saying I saw it in a tube method).

Let me know how you go with the test.

[Malcolm Needs ☆]

Thanks Tim.

After today I am on holiday for a couple of weeks, so I will not be able to do any of this work until I return, and then I would like to get a decent number of samples tested before I say anything, but I will certainly keep you informed of how I am getting on.

Once again, thank for the idea, which I intend to plagerise unmercifully!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[eric1980]

Malcolm.

Note that I was trying to determine the cause of rubbish reactions with fresh serum from clot activator tubes and this in vitro activated complement can really get in the way. It will light up the C3c and C3d columns. If you see it, you can throw the serum into an edta tube for 60 seconds and it will not be seen. Also note that if your cells are in ID-Dil 2, the complement will be neutralised (as if it has edta in it). I think this should be bourne in mind if you are actually looking for complement with these cards. Suspend your cells in some other diluent or it will kill any complement reactivity - in my experience.

I also very heavily coated an RhD+ve cell with a monoclonal IgG anti-D and it all got messy. The control column lit up as did a few of the others. Using routine samples I found no problems and it was very useful.

Of course the other nice thing is that you can take very nice photo records. I have a pic of a very strong anti-Mur that I can show is pure IgG (as opposed to just saying I saw it in a tube method).

Let me know how you go with the test.

A shiver ran down my spine...

I didn't think about the possibility of EDTA neutralising complement. My lab performs monoclonal DAT for complement using a EDTA specimen. My reference lab does the same. I believe this is written down somewhere in the AABB Tech manual. What's going on?! *Is traumatised* =S

[LaraT23]

A shiver ran down my spine...

I didn't think about the possibility of EDTA neutralising complement. My lab performs monoclonal DAT for complement using a EDTA specimen. My reference lab does the same. I believe this is written down somewhere in the AABB Tech manual. What's going on?! *Is traumatised* =S

Methods section pg. 908-909, 17th ed., specimen of choice: EDTA anticoagulated specimen;

DAT, Tech manual 17th ed, pg. 500:

" Although any red cells may be tested, EDTA-anticoagulated samples are preferred; EDTA prevents in-vitro fixation of complement by chelating calcium taht is needed for C1 activation. If red cells from a clotted sample have a positive DAT, the results should be confirmed on cells from freshly collected blood kept at 37C or an EDTA-anticoagulated specimen if those results are to be used for diagnostic puposes"

You need to differentiate between in vivo complement activation and in-vitro. Not a big deal if it happens after the draw in the tube.

Also, the technical manual states that the red cells are washed to remove any complement and or IgG present in surrounding plasma. The plasma contents are what neutralizes, not the EDTA, it just makes Calcium unavailable to the complement "cascade".

[TimOz]

Hi Eric,

Your testing is fine and Lara is correct. BUT "oils aint oils" and plasma is not serum.

If you are doing a DAT you are looking for in vivo binding of complement onto the patient's own red cells. Collecting into edta is preferred as the chelation of calcium will prevent further C' binding and you will see the in vivo C' coating only. The issue is that in an IAT test where you are looking for in vitro antibody binding of an antibody or complement you see a difference between plasma and serum. Some antibodies are so called "complement binding" antibodies and may be detectable in serum but undetectable in edta plasma. The classic antibody that is relatively common that behaves like this are Jk antibodies. If you collect into edta (or use reagents like red cell diluents or LISS additivies with edta) you will see reactions equivalent to edta plasma and while this is not considered to much of a problem, you should certainly be aware of this.

As Malcolm Needs says: "you should understand the principles of your tests" but this also includes the characteristics of the samples you are using. It seems to me that some manufacturers don't help much in this area and their training and technical materials don't make it easy for users to understand how things work. As an example, I mention above that if a red cell LISS Additive reagent has edta in it, the users really need to know this to understand the serological reactions they are seeing. You are less likely to see in vitro complement activation interfering in your tests BUT you are also less likely to pick up complement binding Jka antibodies. That is fine if it is an informed choice. If you use such a reagent and use Polyspecific cards for IAT testing you should be aware that the C3d component will show nothing (except perhaps a DAT positive patient Auto or a DAT positive unit in a crossmatch).

[Brenda K Hutson]

We too would give cross-match compatible random units.

We are a little more careful with anti-M, in that we will make certain that it does not react at 37oC.

I was on-call about a month ago and had to deal with a patient with a pan-agglutinating auto-antibody and known underlying alloantibodies. Having performed multiple differential alloadsorptions, there were still some extremely strong reactions that did not pattern for the known antibodies.

After a couple of hours, and much scratching of the head, I was bale to prove this to have a specificity of anti-M. It was amazing. It reacted 4+ in pre-warmed, warm-washed LISS tube IAT, using a monospecific anti-IgG reagent and, in my opinion, would have been very clinically significant. I've never seen an anti-M like it before.

In this particular case I made sure that the units were M-. I wasn't prepared to do an in vivo cross-match on that little blighter!!!!!!!!!!!!!!

When I was a Reference Lab Supervisor at the Red Cross, we actually had 2 sites in the local area that I oversaw (large area so centers far apart). Anyway, I was more frequently at one center than the other, just because it was headquarters. One day I went to the other center just to check things out. I was reviewing a work-up the Tech. there did on a patient with multiple antibodies; among them, Anti-M. Obviously a patient with multiple antibodies (and we are talking maybe 5) plus an Anti-M would be difficult to find blood for. I asked her if she tried to prewarm it. She said Yes and that it was prewarm positive. I then told her that we needed to honor the M then. Unfortunately, she had already sent blood to the Hospital that was negative for everything else, but not the M. I asked her why she did that; she said it was too difficult to find blood. I told her that next time, she needed to find the blood. Much to my embarrassment, the patient was transferred to a local Hospital (where I had previously worked) and they eluted an Anti-M! Aaahhh

Brenda Hutson, CLS(ASCP)SBB

[Judy hedglin]

If the M spills to AHG, M negative, crossmatch compatible untis. For the others..crossmatch compatible through all phases.