Probable A3B

[Learning from the experts 5]

For an A3B patient, is it common to get MF with anti-A reagent only and no MF with anti-A, B? We tested the sample with multiple sources of Anti-A, Anti-B and Anti-A, B. MF is seen only with -A reagent. 

 

[yan xia 193]

Because of the normal B antigens on the cells, so we can see strong reaction on MF with anti-AB.

Edited May 1, 2019 by yan xia

[noelrbrown 33]

Be aware that most Anti AB these days is a blend of anti A and Anti B monoclonal and is not strictly an anti AB.

[Malcolm Needs ★ 4,878]

Don't forget, also, that an individual who is AB has the A and B antigens on each and every erythrocyte.  The antigens themselves are NOT direct gene product, as they are, in effect, immunodominant sugar residues, and only proteins can be direct gene products.  In the case of the A and B genes, the direct gene products are, respectively, N-acetyl-D-galactosaminyl transferase and D-galacosyl transferase, both of which transfer their respective sugars from a UDP donor molecule.  However, these two enzymes are competitive.  As a result, sometimes the A transferase "wins the battle" between the two, and the A antigen ends up being expressed more strongly on the red cells than the B antigen, and sometimes the B transferase "wins the battle" between the two, and the B antigen ends up being expressed more strongly on the red cells than the A antigen.

In the case of the latter, an individual who is genetically A2B can, phenotypically, appear to be A3B, and so genotyping the individual may not help.  All that having been said, the fact that (roughly speaking) 50% of the antigens expressed on each red cell will be a normal B antigen, it is not surprising that there would be no"mixed-field" reaction with anti-A,B.

[Learning from the experts 5]

Thank you, guys, for explaining.