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Anti-H and anti-HI


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I am trying to get anti -H and anti-HI correct in my head and can't find any good articles on it. 

I wanted to check.

Is it only Bombay phenotype that can produce a true allo anti-H and require I negative blood?

In Para Bombay is it only A1, A1B and B that can form a weak reacting anti-H and is it really auto anti-H? For transfusion they would get 37°C IAT compatible and  never A2 or O?

The same goes for anti-HI. Is it only para Bombays that produce this. Is it really auto  or can normal A1,A1B and B individuals produce it too. 

Is there such a thing as auto ant-H and HI in group O individuals?

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3 minutes ago, catm said:

 

Is it only Bombay phenotype that can produce a true allo anti-H and require I negative blood?

Yes, it is only a true Oh individual ("Bombay" is the wrong nomenclature.  This misnomer came about because the first few individuals with this phenotype all came from around that area of India, and this is now named Mumbai anyway, but the Oh phenotype has now been detected in many other populations around the world) who can produce a true allo-anti-H, however they do not need I Negative blood, but most certainly do need H Negative blood, and so can only safely be given blood from another Oh individual.

In Para-Bombay is it only A1, A1B and B that can form a weak reacting anti-H and is it really auto anti-H?

"Para-Bombay", like "Bombay" is now not used.  The terminology used now is Ah or Bh (you would be lucky to find an individual with the AhBh phenotype as, as far as I know, nobody of this type has been described).   There is some dispute over the genetic background to these individuals.  It is probable that they have a silent FUT1 (or H) gene, but a functioning FUT2 (or SE gene), and so the individuals will produce soluble A or B substance (Type 1), but not the insoluble type of A or B that is intrinsic to the red cell membrane (Type 2).  It is believed, therefore, that the A or B antigens that are found on the red cells of Ah and Bh individuals are actually adsorbed onto the red cell surface from the plasma.  Such individuals would, of course, also secrete a small amount of H substance into the plasma, and this would also be adsorbed onto these red cells.  This complicates matters, with regard to what kind of anti-H is produced.  Certainly, it is usually weak, but is it an auto-anti-H or an allo-anti-H?  The answer is a "bit of a lemon"!  It is probable that such individuals produce an allo-anti-H directed against the Type 2 H antigen, but could also make an auto-anti-H against the Type 1 H antigen.  However,as the Type 1 and Type 2 H molecules are very similar to one another (The Type 1 molecule having a beta-1-3 linkage between the terminal D-galactose and the sub-terminal N-acetylglucosamine, whereas the Type 2 molecule has a beta-1-4 linkage between these two sugar residues - otherwise they are identical), and this may explain the weakness of the anti-H produced.

All that having been said, some workers think that a weak H antigen, intrinsic to the red cell membrane (Type 2) may be produced in certain circumstances, if the mutation to the FUT1 gene does not produce an absolutely null fucosyltransferase, but produces a fucosyltransferase that can produce the H antigen, but only in very small amounts.  If this were the case, then both the anti-Type 1 H and the anti-Type 2 H would both be auto-antibodies.

For transfusion they would get 37°C IAT compatible and never A2 or O?

Transfusion of these individuals is complicated!  If time allows, I would always transfuse cross-match compatible group Oh blood.  If the situation is urgent, then I would give group O blood, even though there is a weak anti-H present, but cover with high dose IVIgG, and keep my fingers, toes, arms, legs and eyes all crossed!

The same goes for anti-HI.  Is it only "Para-Bombays" that produce this?  Is it really auto-, or can normal A1, A1B and B individuals produce it too?

Here, I am glad to say (actually, immensely glad to say) we are on safer ground!  Anyone, of any common or uncommon blood type, including group O individuals, can produce an anti-HI, and this is ALWAYS an auto-antibody (on the grounds that an Oh individual, who is also an adult ii individual has never been described - and probably never will be - and this would be the only person who could possibly make an allo-anti-HI!).  There is not an awful lot more to say about that!

Is there such a thing as auto ant-H and HI in group O individuals?

Yes, there is such a thing as auto-anti-H in a group O individual, but it is disappearingly rare (as is auto-anti-A in a group A individual and an auto-anti-B in a group B individual).  On the other hand, an auto-anti-HI is not uncommon in group O individuals, although it is rarely clinically significant (only really in cases of CHAD) and, in healthy individuals, you would usually have to perform some "exquisite" serology to prove it was present.

There, I hope that helps!  Of course, othrs may not agree with what I have written.

 

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