I had a patient that had an ABO discrepancy. Testing is as follows:
anti-A: 4+, anti-B: 4+, A1 cell: 1+s, B cell: 4+, Screen cells I.S.: all negative, LISS 37: all negative, poly AHG: all negative. Group O donors I.S.: negative, Group A donors: 1+ to 2+. Saline replacement for A1 and group A donors: negative. Microscopically, the A1 and A donors do not really appear as rouleaux. So the question is why do we see apparent rouleaux only with the A cells and not the screening cells?