Hi, there thanks everyone for help in the past btw. I love BB but it can be overwhelming when we have so many classes and I feel we really do not get enough time to soak in the material at all. Just trying to stay afloat. Ok so, I'm stumped with this case study I would appreciate any help. A man was typed as A,B, negative. No other immunologic tests were done because the patient went into shock from blood loss and needed transfusion STAT. No antibody screen, no crossmatch was done. The bloodbank had no A,B negative blood so they gave him 6 units of O neg. Some days later he is still "bleeding". The MD says that this patient now needs 6 more units of packed cells and 4 units of plasma. The results of ABO RH typing on UNwashed cells were as follows: anti-A: 2+MF anti-B: 2+ MF A1 cells: 1+ weak B cells: 1+ weak auto con: 1+ MF anti-D: 1+ MFA Weak D: 2+ MFA DAT: 2+ MFA Ok, I'm sorry that this is so long but i cannot ask the question without giving you this information. I know that this patient's ABO type is probably A,B, weak D. I also know that this patient probably has an unexpected antibody because the DAT was positive. I know that we are seeing MFA on forward typing because the patient has 2 populations of blood cells in his system. My question is why is the reverse typing done with the A1 and B cells positive? The O cells have no antibodies in them because it was packed cells which were given and the donor is always tested for bound antibodies if I am not mistaken. So, why the MFA with the A1 and B cells please explain. thanks in advance for any help