A2: The flow crossmatch (XM), or a cell-based assay = donor lymphocytes + recipient serum (may contain antibodies) ➡️ wash + fluorescent IgG ➡️ flow cytometry
Enter: complement dependent cytotoxicity (CDC) XM
Basically, repeat the flow XM above. But instead of adding a fluorescent IgG, add #complement!
Remember that the flow and CDC XM may be positive if there are non-HLA antibodies against the donor's lymphocytes...