Malcolm Needs

ALG is anti-lymphocte globulin and ALT anti-thymocyte globulin. These are heterophile antibodies that are given to patients as treatment (or, rather, part of treatment) and, when first given, often cause a positive DAT, which disappears relatively quickly in vivo, so that blood taken immediately after dosing has a positive DAT, but blood taken a little later has a negative DAT. There may well now be other such drugs, as I came across this effect a few years ago now.

I, for one, appreciate your further thoughts. I am still thinking myself (but, really, I am as baffled as you about Case 2 (unless the patient was given something like ALG or ATG as part of his therapy).

I think this is highly dangerous, and I also think that your Pathologist should tell your "LEAN" department to butt out, if you will excuse the language.

We still use 32 for our gel titres in the UK (except for anti-K and Kell-related antibodies, but even 32 seems to be "belt and braces" for most antibodies outside of the Rh and Kell Blood Group Systems - although not all).

The only reason I asked was because both ALG and ATG can cause a transient positive DAT that will become negative within a couple of hours of administration.

Good for you, and I hope you thoroughly enjoy your retirement (but keep posting on here!).

BankerGirl, was your patient on something like ALG or ATG?

I would totally agree with Yanxia about Case 1 probably being an ABsubgroup as being the most likely answer to your first case, but it would be wonderful if you were able to follow up the case at six months, just in case it is a genuine case where the B transferase is so "weak", that it is almost "overwhelmed" by the A transferase. Another possible explanation, one which is unusual, but not unknown with monoclonal ABO antibodies (and will not be popular with the manufacturer of your ABO reagents!), is that your anti-B is actually an anti-B(A), whereby the anti-B is capable of reacting weakly with group A red cells (the opposite can also happen with anti-A(B) whereby an apparent anti-A can react weakly with group B red cells). Case two is very intriguing. I would echo that anti-Lua is not what would generally be considered to be clinically significant. There certainly appears to be an anti-Lua there, which is sensitising his red cells in vivo, which may well have been introduced by transfusion of another component (given his pathology, I am assuming that he has received more than just this unit of platelets within fairly recent times). However, it could well be that the plasma from this particular unit of platelets could have contained an antibody directed against a completely different low-prevalence antigen, such as an antigen within the 700 series. If this is the case, even a relatively large Reference Laboratory may well have grave difficulty in identifying the specificity, as they may not have access to red cells expressing the cognate antigen. In addition, such antibodies often cross-react with multiple low prevalence antigens, and, on top of that, individuals who make such antibodies often produce multiple antibodies directed against actual low-prevalence antigens (by that, I mean that this is not cross-reactivity). This would explain the positive DAT. Some of these antibodies do cause red cell destruction, which would explain the later negative DAT, but not to such an extent that you would see symptoms such as dark urine. Obviously, I have no idea of the drugs he is taking, but this doesn't sound like a drug-induced reaction to me, as I would certainly expect to see dark urine, and other evidence of haemolysis.

Great cases Brenda. I am at work at the moment, so I will have think and post tomorrow if I come up with anything - but don't hold your breath!

Just SO true Mabel.

In the circumstances (I don't live in the USA, so I would never be "In the circumstances"), I would be more keen to charge the MD who has changed his or her mind, rather than the patient!

I have never seen this phenomenon interfering with titre results. That is not to say it couldn't happen - it just means that I have never seen it.

Welcome to this wonderful site jammartinez760.

We did virtually the same (when I was young enough to work in a hospital laboratory), but the exception was that we would perform a cord workup on babies who were group B, when the mother was group O AND from one of the Black populations.

IN the UK, the NHSBT (at least) has been performing titrations of all antibodies, of all specificities, in gel, after an extensive amount of work performed by my friend Gordon Burgess showed that there was very good correlation between these titres and those obtained by tube technique.