Revealing and quantifying polyclonal anti-A, B specificity in ABO histo-blood groups

The clinically significant antibody anti-A,B together with anti-A and anti-B has been known for many decades to be present in blood group O plasma. As anti-A,B is only reactive when an A or B antigen is present, its contribution to titer cannot be easily distinguished from anti-A and/or anti-B.

Chemically synthesized AB epitope (ABep) was attached onto red cells creating ABep-kodecytes; methodology was optimized and then used together with group A- and B-kodecytes to semi-quantitative undiluted plasma samples of all ABO blood groups for anti-A, anti-B, and anti-A,B. Standard titers with plasma dilutions against natural A₁ and B cells were performed in parallel.

ABep20-kodecytes were able to semi-quantitate anti-A,B independently of anti-A and anti-B. Anti-A and anti-B levels were also able to be inferred by deduction of the anti-A,B contribution. There was a large range in the levels of anti-A,B in the group O samples, including in those determined to have high-titer ABO antibodies. Unexpectedly, some group A, B, and AB individuals were also found to have an anti-A,B-like antibody.

Anti-A,B is a much more complex antibody than current understanding, and shows a range of activity over a large continuum, which includes in vitro detectable anti-A,B-like antibodies in non-group O samples. The ability to measure anti-A,B independently of anti-A and anti-B levels may be useful in evaluating clinical associations.