dgibaud Posted November 3, 2011 Share Posted November 3, 2011 Had a cord blood submitted today and got a mixed field rxn (2-3+) in the anti-A column. The tube confirmation was 3-4+. No other problems in the card. The baby appeared to be rh neg, with a neg DAT. The mom was A neg. This could be an example of mixed mom and baby blood. Any other thoughts?Don Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 3, 2011 Share Posted November 3, 2011 Had a cord blood submitted today and got a mixed field rxn (2-3+) in the anti-A column. The tube confirmation was 3-4+. No other problems in the card. The baby appeared to be rh neg, with a neg DAT. The mom was A neg. This could be an example of mixed mom and baby blood. Any other thoughts?DonHi Don,It could be, but I think it much more likely not.What must be remembered is that the A antigen is not a direct gene product from the gene inherited from the parents. The gene itself must, by definition, produce a protein and, of course, the A antigen is, in effect, a sugar.The gene produces an alpha-1-3-N-acetyl-D-galactosaminyl transferase that transferse the N-acetyl-D galactoseamine sugar residue onto the Type 2 backbone for the red cell intrinsic A antigen from a Urindine carrier molecule. The transferase enzyme has not reached its maximum kinetic potential at birth, and so the number of A antigen sites on the red cell of a group A newborn baby (or its cord blood) is nowhere near the number of A antigen sites on the red cells of a group A adult.It is more likely, therefore, that it is just that the enzyme has not yet reached its maximum kinetic potential.The same applies for group B.Other things it could be are very rare, such as an A3 baby, or a chimera, but, I repeat, these are very rare. Link to comment Share on other sites More sharing options...
Rh-fan Posted November 3, 2011 Share Posted November 3, 2011 I thought that the H enzym was not fully functional and therefore the A/B antigens are weaker at birth. I know they have a weaker H antigen also, but it can be the combination of those to. Before stepping to A3 I think you have to stop by at the A2 possibility. A2 is weaker in combination with an already weaker expression of A, an A2 can give these kind of weak reactions and in gel it looks more like mixed-field than in tube. Link to comment Share on other sites More sharing options...
dgibaud Posted November 4, 2011 Author Share Posted November 4, 2011 Went back and checked the sample w/anti-A1 lectin. It was negative so presumably this is an A2 baby. Didn't think I'd get such weak reactivity in gel, but it's good to know if this should happen again.Don Link to comment Share on other sites More sharing options...
Rh-fan Posted November 4, 2011 Share Posted November 4, 2011 The A antigen in newborns is weaker and the A1 antigen will never be present in a newborn, so this can not be used to determine the A1/A2 status. For that you have to wait till the baby is older. Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 4, 2011 Share Posted November 4, 2011 The A antigen in newborns is weaker and the A1 antigen will never be present in a newborn, so this can not be used to determine the A1/A2 status. For that you have to wait till the baby is older.I wouldn't quite say "never", but, otherwise I agree. Link to comment Share on other sites More sharing options...
Yanxia Posted November 5, 2011 Share Posted November 5, 2011 We use gel card to type the newborn, sometimes we get the same result as dgibaud described, we will type the baby's blood with reagent use the plate , just mixed them and to see if the reaction is weaker than normal, because this method is not sensitive to reaction, so to differ the normal and weak reaction is very useful. Link to comment Share on other sites More sharing options...
Mabel Adams Posted November 8, 2011 Share Posted November 8, 2011 Isn't there less branching of the H antigen in newborns (or the substrate below it that I can't remember right now)? This is the same subtrate the I antigen attaches to which explains why cord blood types I neg. Maybe someone with a better memory or a book can clarify what I am trying to dredge out of my old brain (slightly younger than Malcolm's or John's so my antigens aren't so faded yet--if this seems nonsense it is because it is a joke from a different thread.) Link to comment Share on other sites More sharing options...
Rh-fan Posted November 8, 2011 Share Posted November 8, 2011 There is no branching in the H antigen, like in I. There are other types of H, and one is type 3 that is a repeated form of H that is made from A type 3, form this H it is possible to make A (type 3). This a repeated form form of A, and can seen as a kind of branching. This form A you will only find in persons with an A1 enzyme, because the A2 enzyme is capable of transforming H (3) into A(3). Link to comment Share on other sites More sharing options...
Auntie-D Posted November 8, 2011 Share Posted November 8, 2011 Was it cord blood? Any chance it could be Wharton's Jelly contaminations. Has the sample been repeated? Link to comment Share on other sites More sharing options...
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