Yanxia

Hi Steve,
I'll give it a go anyway!
Almost everyone in the world is positive for the LW(a) antigen (and a few for the LW( antigen. However, auto-anti-LW (I use the generic term, because very few have ever been differentiated into auto-anti-LWa or auto-anti-LWb) is quite a common specificity in AIHA (again, how common, I couldn't say, because most of the time, we don't bother going for the specificity, because it would make no difference to the clinical treatment of the patient), and, in some cases, the patient becomes transiently serologically LW weak or LW-. It is unclear as to whether the red cells are actually LW weak or LW-, or just that the antigen sites are blocked by the auto-antibody, but, again, so what!
Anyway, as you know, anti-LW reacts very much like anti-D, except that D- red cells, like D+ red cells, are also LW+, but have weaken expression of the LW antigen.
This is because the number of LW antigen sites on D- red cells (average 2835) is much less than on D+ red cells (average 4400 sites); hence it can look like anti-D.
Very often, when red cells are treated with papain, the anti-LW will react equally strongly with D+ or D- red cells, BUT by IAT, the anti-LW will react much more strongly with the D+ red cells than the D- red cells (essentially, you get no visible reaction).
Now then, for some reason, the LW antigen is expressed MUCH more stongly on cord red cells, again, because of the number of LW antigen sites (average 5150 for D+ cord blood cells, and 3620 for D- cord blood cells).
AS you can see from these figures, the number of LW sites on a D- cord blood cells (3620) is higher than the number of sites on an adult D- red cell (2835) and, although not as high a number of sites as on an adult D+ red cell (4400), will often react visibly with an anti-LW by IAT. D- cord blood cells will not, of course, react with a true anti-D, therefore, if a group O, D-, DAT- cord blood cell reacts by IAT with an antibody that looks like an anti-D (but anti-D is unlikely, from the patient's history), then there is an excellent chance that the true specificity is anti-LW.
I hope that helps??????????
:whew::whew:

If it was that urgent a case, I can't see what else you can do, because thawing a pp unit that may not be necessary would be a terrible waste.

If a transfusion is required and urgent (severe symptomatic anemia), a X-match in IAT at 37°C may be tested. You do not necessarily need P-negative blood (very scarce) unless severe transfusion refractory anemia which would support the need of P negative units. For transfusion, patient should be placed in a warm environment and ensuring that the transfused blood is (pre)warm as well.
Hereunder are some references:
Clinical and epidemiological features of paroxysmal cold hemoglobinuria: a systematic review - PMC
Autoimmune Hemolytic Anemia and Red Blood Cell Autoantibodies | Archives of Pathology & Laboratory Medicine

It is my understanding that, while resistant, it is not totally unaffected and can even be enhanced due to cleavage.
From the internet search:
Rh Antigens and Papain: While intact Rh-positive red blood cells treated with papain may not show a change in the size of the Rh-containing polypeptides, sequential treatment with phospholipase A2 followed by papain does result in cleavage of a 35-Kd protein band to a 30-Kd band, suggesting some effect on the Rh-related polypeptides.
Increased Agglutination: Interestingly, papain treatment often leads to enhanced agglutination (clumping) of red blood cells by anti-D antibodies. This suggests that while the D antigen itself might not be entirely destroyed, the changes in the red cell membrane caused by papain somehow make the antigen more accessible to the antibody or enhance the agglutination process. One theory is that papain modifies the red cell surface, reducing its electronegativity and exposing hidden antigens. 
Here's a couple of articles discussing:
https://www.sciencedirect.com/science/article/pii/S0006497120626842
https://www.sciencedirect.com/science/article/pii/S0006497120858455#:~:text=studies%20described%20here.-,RESULTS,produce%20other%20detectable%20cleavage%20products.
Very interesting ... thank you!

I can't recall having come across an anti-D reacting like this (as far as I can remember these days - which isn't very far at my age!!!!!), but I do remember once finding an anti-E that only reacted by IAT, and not with enzyme-treated red cells, which I sent to the International Blood Group Reference Laboratory for confirmation, and it was confirmed by no less a person than Joyce Poole. We published a poster about it at a BBTS Annual Scientific Meeting (MacRate EB, Carrington T, De Lord C, Needs M, Win N.  Anti-E Detectable by IAG and Not by Enzyme?  How Confusing!  Transfusion Medicine 2001; 11 (Suppl. 1): 30.).

Arndt PA, Garratty G, Marfoe RA, Zeger GD.  An acute haemolytic transfusion reaction caused by an anti-P1 that reacted at 37 degrees C.  Transfusion 1998; 38(4): 373-377.  DOI: 10.1046/j.1537-2995.1998.38498257376.x.
Smith D, Aye T, Er LS, Nester T, Delaney M.  Acute hemolytic transfusion reaction due to anti-P1: a case report and review of institutional experience.  Transfus Med Hemother 2019; 46: 381-384.  Published online as DOI: 10.1159/000490897.
Irani MS, Figueroa D, Savage G.  Acute hemolytic transfusion reaction due to anti-Leb.  Transfusion 2015; 55: 2486-2488.  DOI: 10.1111/trf.13178.
Delk AA, Gammon RR, Alvarez H, Benitez N, Bright F,  A hemolytic transfusion reaction caused by an unexpected Leb antibody.  Laboratory Medicine 2021; 52: 303-306.  DOI:  10.1093/labmed/lmaa070.

I'm sorry Neil, but Geoff Daniels quotes some HTR's caused by anti-N reacting at 37oC, and one case of mild HDFN in a M+ N+ baby, where the mother was M+ N-, S-, s- Uvar, in the third edition of his book, Human Blood Groups.

For acquired maternal IgG antibodies (which may also be transferred postnatally through breast milk), assessing the antibody specificity (AbS) in the newborn, as previously mentioned, appears to be a reasonable approach. In addition, the Direct Antiglobulin Test (DAT) remains key, and performing an elution is important (even if the DAT result is negative). In your case, the negative DAT suggests that either the anti-N antibody did not cross the placenta, possibly due to being a naturally occurring IgM, and/or the baby is N-negative.

In that case, I would consider a genotype, as getting hold of M+ N-, S-s-U- fresh units is not going to be easy. That having been said, as you say yourself, anti-N is rarely clinically significant and, if it is not detectable in either the maternal circulation, or in the baby's circulation, I wouldn't worry too much about giving M+, N-, S-s-U- blood. BEAR IN MIND THOUGH, THIS WILL BE A CLINICAL DECISION, AND I AM NOT, AND NEVER HAVE BEEN, MEDICALLY QUALIFIED.

The reason I said this (and I admit that I am being more than a little "Reference Laboratory Pedantic here) is because a very good friend of mine (Edmond Lee, who used to work at the NHSBT-North London Centre at Colindale, with such luminaries as Prof Dame Marcela Contreras, Dr Mahes de Silva and Martin Redman, amongst others, who described a case where the bay of a woman with an extremely strong anti-K,, where the baby's foetal K antigens were blocked by the maternal anti-K, and so tested as negative (Lee E, Redman M, Owen I. Blocking of fetal K antigens on RBC by maternal anti-K. Transfus Med 2009; 19(3):139-40. doi: 10.1111/j.1365-3148.2009.00917.x. Later, he reported the same sort of thing with a maternal anti-Fy(a) (Lee E, Cantwell C, Muyibi KO, Modasia R, Rowley M, New H. Blocking phenomenon occurs with murine monoclonal antibodies (anti-Fya) in a neonate with a positive direct antiglobulin test due to maternal anti-Fy(a). Blood Transfus 2015; 13: 672-674. doi: 10.2450/2015.0232-14.

Obviously, in both these cases, the maternal antibody was easily detectable, so not the same as the case being described by BullDawgPath, and, in both cases, the baby's DAT was positive, BUT, in both cases, antigen negative blood was required by the baby.

It is incredibly rare for anti-N to be an alloantibody, unless the individual is M+N-, and also S-s-U-. This is because the amino acids that characterise the N antigen on the Glycophorin A molecule (leucine, serine, threonine, threonine, glutamic acid) are identical to the amino acids that characterise the 'N' antigen on the Glycophorin B molecule.

Is the lady of Black ethnicity by any chance? If not, to be N Negative AND 'N' Negative would be almost unique.

This suggests to me that the anti-N reported to be in the maternal circulation by the other hospital may well have been an auto-antibody, and would almost certainly be sub-clinical in its significance. In such a case, I would not bother with performing genotyping of the baby's N type. However, as far as Rh, K, etc, I would certainly suggest that antigen negative blood is given to the baby, and I certainly WOULD perform foetal genotyping (see my answer to Cliff above).

All great questions, but I would also ask, what is the baby's Hb/Hct requiring a transfusion, and why not test the baby's DNA for the gene encoding the antigen cognate to the maternal antibody?

Couple of questions for clarification. What is the specificity of the known Alloantibody? "Baby is born and our testing shows negative antibody screen." Was this AB screen done on mom or baby? If on the baby, was a current ab screen performed on mom and if so what was the results? Was a DAT performed on the baby? If so, what was the result? If not, why not? Thanks

What? All this time I have been using the wrong stuff! Ha! SPELL CHECK IS NOT YOUR FRIEND! 🤣🤣🤣🤣

Um, sorry Jason, but I think you mean Dithiothreitol (DTT), rather than Dichlorodiphenyltrichloroethane (DDT)!!!!!!!

Also, were any of the transfused units antigen positive? This is the quickest way to get a negative indirect antiglobulin test ;).

How many units of uncrossmatched blood did they receive? How active were they bleeding? How much later did the other hospital preform their own T&S? Inquiring minds want to know!!! 😉

I agree Darin, it is almost certainly a dilutional effect, BUT, it could also be the effect of a soluble antigen (obviously not within the Duffy Blood Group System). If the antibody had a specificity within, for example, the Lewis Blood Group System, or the Chido/Rodgers Blood Group System, the antigen in the plasma could well adsorb out the circulating antibody. That having been said, this explanation is FAR less likely than your suggestion of the dilutional effect.

My greatest apology for leaving you all hanging. We've been so incredibly busy and short-staffed that I could not even think about anything else but trying to finish up my daily duties. Anyway, seems that the patient also had an impella device that had to be "adjusted" and I believe that corrected the hemolysis. I'm only reading the responses today (2 weeks later)☹️so hats off to you all who thought mechanical causes. I would have not thought that the device would be that far-off to cause the gross hemolysis we saw. We do see slight hemolysis with impella devices but not like this one. I guess never say never. Thank you all for your responses.

We have seen this phenomenon from time to time, albeit rarely. We use R1wR1 red cells with all of our antibody identifications, purely because it is always cell 1 in the panel! We also, however, use two R1R1 panel cells and an r'r panel cell.
I'm not too sure why we get the odd sample that reacts like that, because the C antigen on the R1wR1 panel cell is not that much weaker than the C antigen on the R1R1 panel cells, and certainly no weaker than that on the r'r panel cells.
Remember that the "w" of "Cw" stands for "Willis", and not "weak", as it was named after the donor who caused the immunisation to the antigen in the first example of anti-Cw described (something I forgot a few years back in an article I wrote, much to my embarrassment, if that is any solace to you) and that RH8 (RHCw) is allelic to both RH9 (RHCx) and RH51 (MAR), and not to either RH2 (RHC) or RH4 (RHc). Therefore, any weakening must be due to steric hinderance, or something similar.
:confuse::confuse:

At our facility, we have to do a cold adsorption IF the cold auto interferes with the reverse and/or ISXM. Since testing with "neat" plasma is our standard of practice, we would still report the XM as incompatible and send it out with a release stating the incompatibility was due to an autoantibody. We are not "allowed" to prewarm away IS reactions. 🥶 IF we prewarm - it's only if the cold has a high thermal amplitude and causes interference after 37deg incubation / antiglobulin phase...........but that's just us.........

Happy Friday everyone! 
First off, Thank you Malcolm 😊 for that excellent PPT lecture! 👌 With your permission, I'd love to share it with my students; it's exactly the kind of content that helps bring these complex concepts to life (and mildly melt brains in the best way possible).
Speaking of melted brains… let's talk Anti-G differentiation, shall we? While I agree that differentiation isn’t necessary for transfusion purposes because in cases where anti-G is suspected, the recommendation is the same (D and C antigen-negative PRBCs); in the US Reference Lab world, it's a whole different dance. Differentiating anti-D + anti-C from anti-G is essential in alloimmunized patients with anti-D + anti-C for Rh Immune Globulin (RhIg) prophylaxis administration indication. Medical teams want to know if a patient is a candidate for RhIG, and if it's still indicated, especially to avoid future medical and legal complications. And so begins the beautiful (read: painstaking) double adsorption and elution process. 😫
 
The presence/development of a real anti-D indicates the patient does not require RhIg administration, whereas the presence of anti-G indicates the need for RhIg prophylaxis. That way, RhIG is avoided in patients with a real anti-D (although clinical correlation is recommended to guide every decision).
In this case, we saw what looked/reacted like anti-D and anti-C (1). Adsorption with R2R2 cells showed anti-C in the adsorbed serum (2) and anti-D and/or G in the adsorbing R2R2 cell eluate (3). Usually, we would stop and call anti-C and anti-D, if we have no reactions on C Ag Pos cells, but since suspected anti-G was in the mix, we routinely differentiate/separate it. The anti-D was confirmed in (4) by adsorbing the eluate containing the suspected (anti-D + anti-G) with an r'r unit. So far, so good. However, when we tried to separate the anti-G by elution of the adsorbing r′r cells, expecting a reaction on D and C antigen-positive cells (5), we got a negative result (Cue dramatic music).
I know, I know...at this point you’re probably wondering if we’re still in the Blood Bank or if we’ve accidentally wandered into theoretical physics. Trust me, my brain also wobbles when explaining G differentiation. It's the kind of thing that makes you rethink your career choices... for about 5 minutes... and then roll up your sleeves and start prepping another adsorption. 😅
A couple of housekeeping: We ficin treat our adsorbing cells, and sometimes use PEG in adsorption for efficiency. After briefly considering a career in something less chaotic, we retraced our steps. No PEG this time, 60-minute incubation, followed up with a DAT after each adsorption to check for antibody coating... and voilà: finally got the positive reaction we were looking for. The patient has anti-D, anti-C, and anti-G.
I can only think of a possible weak DAT strength pending elution, or PEG interference when used in adsorption. As always, this is Blood Bank, we know a million things can go wrong, and often do. But in the end, science (and a lot of perseverance) wins. 
Thanks again to everyone for your input, patience, your brains, and your sense of humor. And again, Malcolm, thanks for your lecture, teaching, dedication and inspiration!
I wish everyone a calm weekend. May your panels be clear, your DATs negative, and your eluates informative. 😉
 

In our lab, we do 30 patients ABO typing daily in average. In those tests we will find out forward and reverse typing mismatch at least once daily. Maybe because we tested patients' sample, the incidence is higher than donors', but just as Malcolm said it is definitely necessary to do forward and reverse typing and make sure they are matching.

In the UK, we would test serum/plasma samples from pregnant patients to see if there was an anti-C + Anti-G, or an anti-G on its own, but if the tests showed an anti-D+C, we didn't go any further to see if there was an anti-G there as well.  I mean, what for?  What difference does it make?

I attach a PowerPoint lecture on the subject I wrote some years ago, but I think it is still pertinent.
The G Antigen and Anti G.pptx

In our lab, we do 30 patients ABO typing daily in average. In those tests we will find out forward and reverse typing mismatch at least once daily. Maybe because we tested patients' sample, the incidence is higher than donors', but just as Malcolm said it is definitely necessary to do forward and reverse typing and make sure they are matching.