Subgroup in a Neonate?

[saralm88]

Hi everyone!

I need some help/ideas today so where else to go but to my friends on here .  A neonate front typing AB + but the Anti-A is 1+ and the Anti-B is 4+.  Both of these were done on heel samples (different draws)and both washed.  I know using Lectin is not ideal because of the weaker expression of antigens on the red cells.  Anyone have any ideas on what I can possible do to try and clear up the reactions or help come to a conclusion?  Any advise and knowledge is appreciated.

Thank you!

[David Saikin]

A ag in newborns are a bit different than adults, e.g., single chain ag vs branched chains in adults.  Personally, I wouldn't be concerned at this time.

[Malcolm Needs ☆]

David is completely correct.

Do not forget, also, the A, B and H antigens are not direct gene products (they cannot be, as they are sugar-residue antigens).  The direct gene products are transferase enzymes (proteins).  These enzymes are not working at their maximum efficiency at birth (hence the weak antigen expression), but, in addition, the "A transferase" and the "B transferase" are competing against one another.  Sometimes the A transferase starts by "beating" the B transferase, in which case the A antigen is expressed more strongly than the B antigen, and, sometimes the reverse is true (as in this case). They eventually "even out", as long as no true subtypes are involved.

Test again at about six months.

[Townsend]

Agree - also, what blood type is the mother?  From an operational stand-point you have a couple of options: Call the blood type "indeterminate" or "unable to determine" or call the baby AB.  Either way, we would suggest repeat testing at 4-6 months and include A1 lectin typing if discrepancy still exists.  In the meantime we would give group O red cells and AB plasma/platelets until resolved.