Hi 

Had a cord blood tested and found mixed field reaction in anti-A.   No transfusion history during pregnancy. Also noticed many new born with no transfusion history have a mixed filed reaction in anti-A and/or anti-B. Is it due to fetomaternal haemorrhage or could be other reason? 

Edited April 22, 20169 yr by gagpinks

I have seen this numerous times and is most likely due to the A antigen not being completely developed on newborn RBCs.   I have seen a fetomaternal hemorrhage do this once in my career but it was detected in the D tube test.   Can you look up mom's HGB pre and post delivery?  

Sorry but what is HGB?

 

hemoglobin

I knew it you probably mean Hb but there will be variations in in Hb in pre and post sample depending on bleeding. How is it related to Hb?

It is almost certainly due to the immaturity of the ABO antigens.

You have to remember that these antigens are carbohydrates and cannot, therefore, be direct gene products.

The direct gene products have to be proteins, and in the case of the ABO, H and Lewis antigens (indeed, any antigen that is carbohydrate, rather than protein based) is a transferase enzyme.  In the case of the A antigen, the transferase enzyme is alpha-1-3-N-acetyl-D-galactosyltransferase that transfers an N-acetyl-D-galactosamine residue from a uridine donor molecule to the subterminal D-galactose residue of either the type 1 or type 2 backbone molecules.  Very often, at birth, the transferase molecule is not working at its full kinetic capacity - which is why you see mixed-field reactions with ABO grouping reagents (and why almost all babies are Le(a-b-)).

Edited April 23, 20169 yr by Malcolm Needs

Thank you Malcolm! !

 

Gestational age also has an impact, I.e., the more premature a baby is the more likely you are to see this phenomenon

24 minutes ago, John Eggington said:

Gestational age also has an impact, I.e., the more premature a baby is the more likely you are to see this phenomenon

Couldn't agree more John - excellent point!

If you had typed the baby's cells with A1 lectin it was probably negative. Some babies will start out A2 and convert to A1 thus giving a mixed field appearance.