We have used Quotient reagents since 2012 without any problems until they began providing poly AHG. In our lab we found poly AHG to be much more weakly reactive, particularly with their C3 check cells. That to the point of having to do the 5 min room temp incubation to get above 1+; the immediate spins were 1+ at the very best. One other reagent we did not like was their anti-D because of their inability to remove a cold reactive antibody that conceivably might cause false positives. The balance of the reagents that we use are ABO antisera and backtype cells, 3 cell screening cells, C3 and IgG check cells, and finally the QC kit.
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?