We have a patient who had an anti-Cw identified 21/2 years ago during routine prenatal testing.  She recently came in to deliver baby #2 and we are still detecting the anti-Cw 4+ in gel (manual method) and 2+ in tube.  We are in the process of validating the Echo and ran her antibody ID on it and the panel was negative with all cells tested, even though there were 2 Cw positive cells on the Ready ID panel.  The fact that we were able to detect the Cw in both tube and gel but not on the Echo makes me nervous.  We did AHG crossmatches and had one donor who was 3+ positive in gel but was compatible on the Echo.  Granted, since we don't have anti-Cw antisera we can only assume the incompatibility is due to the Cw, but this is also concerning me.  Is it possible that the anti-Cw is IgM in nature?  I couldn't find much in the Technical Manual on this antibody.  We are also pretty much out of plasma and the patient has gone home.  Any ideas?  Thanks in advance.

Have you contacted the vendor?  What is their response to this testing failure?

I haven't contacted them yet.  I will update when I get their response.  I was curious after reading a few other posts regarding Echo antibody ids whether this could be explained by the nature of the antibody.  I will post their response when I get it.

Following with interest.

Do you know whether this is a real IgG anti-Cw, or is it an IgM?  the differences might all be due to temperature.

Agreed Anna.

Also following with interest.

Granted you wouldn't want to transfuse known crossmatch-incompatible blood, but perhaps the XMs had been performed on the echo and the incompatible/antigen-positive RBC transfused, what is the likelihood of an actual hemolytic reaction?

 

The Blood Group Antigen FactsBook lists anti-Cw as capable of inducing mild to severe; immediate/delayed reactions while other sources say that there's no evidence of anti-Cw ever causing a hemolytic reaction.

Like you goodchild, I have search all other sources available to me, and the only source that says "mild to severe, immediate delayed reactions" is the FactsBook, but, unlike the others, they do not give references for these reactions.

Our own (NHSBT) Guidelines on anti-Cw, written by Geoff Daniels, certainly allows us to give cross-match compatible blood (cross-matched at strict 37oC in tubes).

I am aware that there is now another case of anti-Cw causing severe HDFN (although I haven't read the paper yet), but that does not mean it would also cause a severe haemolytic transfusion reaction; the two are not inextricably linked.

We had an instance of Cw not coming up on our ECHO panels, but it did with PeG and LISS.  We opened an investigation with Immucor and we even sent our ready ID panel lot and a patient sample to them.  They confirmed the Anti-Cw was demonstrating in PeG and LISS, and not with their solid phase panel.  No other investigation was completed by Immucor on why the antibody was not picked up in solid phase.

Like you goodchild, I have search all other sources available to me, and the only source that says "mild to severe, immediate delayed reactions" is the FactsBook, but, unlike the others, they do not give references for these reactions.

Our own (NHSBT) Guidelines on anti-Cw, written by Geoff Daniels, certainly allows us to give cross-match compatible blood (cross-matched at strict 37oC in tubes).

I am aware that there is now another case of anti-Cw causing severe HDFN (although I haven't read the paper yet), but that does not mean it would also cause a severe haemolytic transfusion reaction; the two are not inextricably linked.

 

Malcolm, because the NHSBT is so generous as to publicly upload their guidance documents, I'm familiar with the document related to clinical significance/Ag-neg vs IAT XM/etc but there's one thing that I've been curious of:

 

For antigens that are deemed IAT XM compatible blood acceptable, is that only if the antibody is 'active' in the plasma?

 

I've been tempted to e-mail the authors of the FactBook for their information relating to anti-Cw specifically.

No, that is whether they are active or not active.

If the antibody is not active, it is going to be clinically insignificant (with the exception of those that are known to cause clinically significant anamnestic responses, such as anti-Jka), but, if you think about it logically, if a patient with one of these antibodies, that is no longer detectable, goes into another hospital, miles away from where they normally go, and that hospital does not have access to the patient's records (may not even know that the patient has ever been transfused or pregnant), then they will get a negative screen, and may even go for electronic issue.

That's what I thought, thank you.

I was able to scrounge up about 2 ml of plasma from hematology and blood bank and have sent this to Immucor for their investigation.  I don't know what they will find out, but suspect that with the age and limitted amount of specimen, they will not be able to do a full investigation.  I will post their response once they get the results.

We received the investigation report from Immucor, and they were able to duplicate our results.  They tested the our panel lot with another anti-Cw and this showed reactivity.  Basically, they said we see what you see, we don't know why, but our product is working.  Too bad there wasn't enough sample to do more investigating.