Flowchart of typical compatibility testing for donors and recipients. Both donor and recipient are ...

Flowchart of typical compatibility testing for donors and recipients. Both donor and recipient are typed for ABO and HLA antigen profiles (steps 1, 2, 4, and 5). The recipient is also tested for antibodies against HLA antigens to eliminate unacceptable donors (step 3). Potentially matching individuals are then tested by cross matching (step 6), which involves mixing recipient sera with donor cells and then adding fluorescence-labeled anti-human IgG and measuring fluorescence by flow cytometry. Seropositivity to cytomegalovirus (CMV) is also assessed for both donor and recipient. When dealing with a deceased donor, results of tissue typing are entered into a national transplantation database.