My friend told me a case : a leukemia patient, anti-A 2+mf, anti-B neg, A1 cells neg, B cells 4+.

Then further test : anti-A1 2+,anti-AB 3+stronger.

I prefer call it antigen reduction ,but I can't explain the anti-AB result is stronger than anti-A and anti-A1.

Edited April 16, 201411 yr by shily

In my experience, reactions with anti-A,B tend to be stronger than with anti-A or anti-A1, even in this era of monoclonal grouping reagents.

I agree with Malcolm in that almost all weak A or B antigens will react better with anti-AB than with anti-A or B alone.  monoclonal anti-AB reagents should be true anti-A,B rather than a mixture of anti-A and anti-B.  The latter are not really worth using.  This could either be a true weak sub type of A; or, as your patient has a leukaemia, it could be the disease that is weakening the antigen. 

I agree with Malcolm and Anna.

Donna