Anti-C in C pos patient with strong e type

[Mabel Adams]

I'm over my head with this case for a Friday afternoon.  Patient is a 70 yo apparently Caucasian female who was transfused in 1981 in childbirth.  No transfusion since. She was in ED for a fall but has been discharged.  Very limited sample volume.  O pos.  Appears to have anti-C reacting 1+ in gel.  Reacts 1+ with another cell that is C neg and HLA pos. HLA is noted as present on 2 of the C+ cells that react but not on the other three C+ cells that react.  Have negative reactions that allow ruling out all of the other usual suspects.  DAT is 3+ with IgG; neg for Complement.  Patient types C+, E+, c+, e+ with the e reacting quite a bit more strongly than is typical with our Ortho anti-e reagent (comes up solid 4+ at immediate spin).  We have not done an eluate, partly because it seems not worth the resources because she has been discharged.  I suspect a mimicking anti-C autoantibody or just Bg antibodies, but is there anything else we should be thinking about?  I get confused in all of the rare Rh variants so thought I would save myself a lot of reading and ask the experts. 

[Malcolm Needs ☆]

I am a complete antibody nerd, but, in this case, I think that you would be knocking your head against a brick wall for no reward if you try to go any further with this one.

My first thought was that it may be a case of an anti-hrB, but when I saw that the patient was a Caucasian, that was virtually "blown out of the water".  Then I saw that she had a positive DAT with anti-IgG, but not anti-Complement, and I thought Rh specificity, and, like you, I immediately thought of a mimicking auto-anti-C.  The problem is that, if you performed an elution, to actually PROVE that was the case, you would have to have access to some exceptionally rare Rh types (red cells that even many Reference Laboratories lack, let alone Hospital Laboratories).

My mentor, Joyce Poole, who taught me so much, taught me (in no uncertain terms!) not to waste such rare red cells, when I was but a young whipper snapper at the International Blood Group Reference Laboratory when it was still in London - and I'm glad she did before her boss, Carolyn Giles, needed to teach me!!!!!!!!!!!!

In this case, particularly as the patient is even older than am I, AND has been discharged, even as an antibody nerd, I would be inclined to let sleeping dogs lie!

[Malcolm Needs ☆]

I've had further thoughts upon this case (having told you not to worry about it - I live a sad life - NOT!).

It struck me that the patient has an Rh type of D+ C+ c+ E+ and e+, suggesting that the probability is that the patient has a genotype of DCe/DcE (R1R2), but this may not be the case.  She could have one of the rarer Rh genotypes, such as DCE/Dce (RzRo), DCE/dce (Rzr), Dce/dCE (Rory), etc, and this may be potentially important.

Some years ago, Joyce Poole explained to me that most grouping reagents labelled as anti-C are, in fact, a mixture of anti-c and anti-Ce, and this, she told me, included most monoclonal anti-C reagents (which surprised me, to be honest).  This is because the vast majority of the red cells transfused that stimulate an anti-C would have the haplotype of either DCe or dCe, or both, and will, therefore, also stimulate an anti-Ce.  As a result, these "hybrid" anti-C/anti-Ce reagents will react more strongly with red cells expressing the Ce compound Rh antigen (Rh7) and the C antigen (Rh2), than with red cells that only express the C (Rh2) antigen.

This would not, incidentally, explain the stronger than normal reaction with the e antigen.

However, if the patient does express one of the rarer Rh types mentioned above, say she is RzRo, she can actually produce an allo-anti-Ce, and most antibody panels only contain C+ red cells that are only Ce+ as well.  In other words, her antibody in the plasma MAY be identified as an anti-C, whereas it is actually a monospecific anti-Ce, which would neatly explain why she has an apparent anti-C.

Of course, she may also have an auto-anti-C, or a mimicking auto-anti-C (and, possibly, an allo-anti-Bg of some sort).  Sadly, for a nerd like me, I doubt if we will ever know!

I think it was John C Staley who once accused me of looking for zebras, when I hear horses hooves (I may be wrong, but I think it was John).  Anyway, this proves that he was absolutely correct about me!!!!!!!!!!!!!!!!!!!!!!!!

[Bet'naSBB]

We'd probably do the eluate.....(but only because we rarely stop working up anything....and if we need to, we grab a CBC sample -if one is available- to do extra testing - but not XMing....before folks start gasping)

My guess is that the eluate would be pos with all cells......if so, we would say that the sporadic reactivity with plasma was warm auto "spilling" into the plasma.....  We would then do a LISS screen with 30' incubation to confirm there are no underlying "real" allo-antibodies.  

[Malcolm Needs ☆]

19 minutes ago, Bet'naSBB said:

We would then do a LISS screen with 30' incubation to confirm there are no underlying "real" allo-antibodies.  

In what way does a LISS screen with 30' incubation "CONFIRM" that there are no underlying clinically significant allo-antibodies present?  I am always happy to learn.

[Bet'naSBB]

On 8/8/2023 at 9:23 AM, Malcolm Needs said:

In what way does a LISS screen with 30' incubation "CONFIRM" that there are no underlying clinically significant allo-antibodies present?  I am always happy to learn.

It really doesn't......not any better than a negative LISS screen "CONFIRMS" that there are no underlying clinically significant allos present on your "average" type and screen patient......you can never be 100% sure.....

Our validations have shown that LISS with extended incubation used with individuals with warm autos and underlying ab's - will - (not always) - demonstrate specific allo-ab activity without the auto ab interference.  If the LISS screen is completely negative, then we make the conclusion that there are no underlying allo ab's and there is only a warm-auto present and we don't have to adsorb.  If the LISS screen shows specificity - the ab is ID'd further using LISS.  If the LISS screen still shows panreactivity, we allo-adsorb using in house produced, papanized red cell stroma.

[Malcolm Needs ☆]

I'm afraid I still can't agree with this methodology, for a couple of reasons.

Firstly, antibody/antigen reactions are, largely, governed by the Law of Mass Action.  As a result, and given a steady state of conditions (e.g. temperature), however long the incubation time may be, once a state of equilibrium is reached, there will be no net gain of antibody coating antigens, however long the incubation time may be extended.

Certainly, LISS will increase the rate of association of antibody and antigen enormously, but this will apply equally to the auto-antibody as any allo-antibody that may be present, however, of course, some antibodies will only react visibly with red cells that have homozygous expression of a particular antigen, and, if such an antibody is present, it will be very difficult to detect in the presence of an auto-antibody, but can still cause a haemolytic transfusion reaction, albeit, usually a delayed reaction, but it can still cause damage to the renal system in particular.

For these reason, I would always perform an adsorption, to get rid of the auto-antibody, even if I had no intention of performing specificity tests on the auto-antibody (although, it goes without saying, I would go all out to try to ascertain the specificity of any allo-antibody detected).

I am trying to write a book at the moment, called "Human Red Cell Serology and Blood Groups for Beginners", and Chapter 2 deals with Serological Techniques.  I attach the draft copy, which also gives relevant references, the odd diagram and abbreviations I use throughout the various chapters.

Chapter 2 Serological Techniques in Routine Blood Transfusion and Red Cell Immunohaematology Laboratories.docx Chapter 2 Serological Techniques in Routine Blood Transfusion and Red Cell Immunohaematology Laboratories Figures.docx Abbreviations.docx

Edited August 9, 2023 by Malcolm Needs

[Mabel Adams]

On 8/7/2023 at 5:09 AM, Malcolm Needs said:

I think it was John C Staley who once accused me of looking for zebras, when I hear horses hooves (I may be wrong, but I think it was John).  Anyway, this proves that he was absolutely correct about me!!!!!!!!!!!!!!!!!!!!!!!!

I've been accused of looking for unicorns when I hear hoofbeats!  

[Mabel Adams]

On 8/7/2023 at 5:09 AM, Malcolm Needs said:

However, if the patient does express one of the rarer Rh types mentioned above, say she is RzRo, she can actually produce an allo-anti-Ce, and most antibody panels only contain C+ red cells that are only Ce+ as well.  In other words, her antibody in the plasma MAY be identified as an anti-C, whereas it is actually a monospecific anti-Ce, which would neatly explain why she has an apparent anti-C.

If this were the case, wouldn't she react with e+ cells as well as C+ cells?  Or does anti-Ce tend to react more strongly with C than with e?

[Malcolm Needs ☆]

15 hours ago, Mabel Adams said:

If this were the case, wouldn't she react with e+ cells as well as C+ cells?  Or does anti-Ce tend to react more strongly with C than with e?

No.  Anti-Ce (anti-Rh7) is an antibody directed against the "compound antigen" Ce.  In other words, the RHC and RHe genes have to be from the same haplotype.  I suppose you could look at the antibody as being analogous to anti-ce (anti-f), which would react with, for example, red cells from an individual who has the Rh genotype of DCE/dce (I KNOW there is no RHd gene!), or Rzr, but not with, for example, red cells from an individual who has the Rh genotype of DCe/DcE, even though both the c and the e antigens are expressed on the red cells.

What I was saying is that anti-Ce, per se, will only react with red cells where both the C and e antigens are derived from the same Rh haplotype (such as DCe), but, unless there is an element of monospecific anti-C present, the anti-Ce will not react with, for example, red cells that are from an individual with the Rh genotype of DCE/dce, as the C antigen and the e antigen are derived from two different haplotypes.  Of course, if there is an element of anti-e as well, THEN the reagent will also react with the e antigen, but anti-Ce is much more frequently a contaminant of an anti-C than is an anti-e.

I'm still not certain I have explained that as clearly as could others, but I am trying my best!!!!!!

[Mabel Adams]

On 8/15/2023 at 7:37 AM, Malcolm Needs said:

No.  Anti-Ce (anti-Rh7) is an antibody directed against the "compound antigen" Ce.  In other words, the RHC and RHe genes have to be from the same haplotype.  I suppose you could look at the antibody as being analogous to anti-ce (anti-f), which would react with, for example, red cells from an individual who has the Rh genotype of DCE/dce (I KNOW there is no RHd gene!), or Rzr, but not with, for example, red cells from an individual who has the Rh genotype of DCe/DcE, even though both the c and the e antigens are expressed on the red cells.

What I was saying is that anti-Ce, per se, will only react with red cells where both the C and e antigens are derived from the same Rh haplotype (such as DCe), but, unless there is an element of monospecific anti-C present, the anti-Ce will not react with, for example, red cells that are from an individual with the Rh genotype of DCE/dce, as the C antigen and the e antigen are derived from two different haplotypes.  Of course, if there is an element of anti-e as well, THEN the reagent will also react with the e antigen, but anti-Ce is much more frequently a contaminant of an anti-C than is an anti-e.

I'm still not certain I have explained that as clearly as could others, but I am trying my best!!!!!!

Ah, I was thinking of it like anti-G, but a haplotype with D but without C is much more common than one with C without e.  Also, anti-Ce isn't reacting with something made by both the C and e genes like with genes for D and C can both make G.  I think.

[mmarquezsa]

El 8/9/2023 a las 12:19, Malcolm Needs dijo:

Wow... Great... it would be nice to have a Book written by Malcolm...
From now on... count on my support and collaboration if you need review or editing of images... even translation into Spanish... here in Latin America we are very interested in learning from the experience of other colleagues internationally...

+56981375261
my email: mmarquezsa@gmail.com

 

Likewise, if I can contribute something for other colleagues, do not hesitate to write...

 

Greetings from Valparaíso-Viña del mar
PhD (c) Msc. TM. Marcelo Marquez Sandoval
Head of Advanced Immunohematology at the Blood and Tissue Center of Valparaíso

 

Edited September 20, 2023 by mmarquezsa