How to determine subgroups of ABO blood groups

[mrkeramati]

We often observed some patients have  ABO subgroups such as A3, Am, A int, Ax, B3  and so on in blood banking. Using some methods such as adding Anti-H, Anti-A1 or Anti-AB to patients RBCs somewhat helps us to make this differentiation. However, I would like a way to differentiate these subgroups step by step so that we can use it in a hospital blood bank.

Edited October 23, 2014 by mrkeramati

[Malcolm Needs ☆]

I am somewhat surprised that you "often" see patients with these subtypes as, working in a very large Reference Laboratory, we see no more than about 2 or 3 a year.

 

That having been said, with the advent of avid monoclonal grouping reagents, it is now almost impossible to assign a specific subgroup to an individual, without the use of molecular techniques.  The old way of assigning such subgroups is somewhat defunct, as the reactions we get with these modern monoclonal antibodies are so much stronger than those seen with human-derived polyclonal reagents (and even then, the "strength of the reaction" tended to vary from one laboratory to another, and from one person in a laboratory to another, as the reading was totally subjective).

 

Personally, I would not now attempt to assign a specific subgroup.  As long as the patient is, say, group A, it really doesn't matter if they are A₁, A₂, A₃, A_x or A_m.  They can still be transfused with group A₁ blood, unless they have an anti-A₁ in their plasma that reacts strictly at 37^oC, and such an antibody is extremely rare.  If there is any doubt, they can be given group O blood.

 

From the donation point-of-view, again it doesn't matter if the donor has a subgroup of, for example, group A; they are still group A, and, as a consequence, their blood should be labelled as such, so that it does not go to a patient who is group O or group B.