CDC Crossmatch(T and B cells)

CDC-XM uses donor lymphocytes (T and B lymphocytes) as targets to detect DSA in the patient’s sera. Antibody-antigen immune complex in turn can activate the classical cascade of complement activation leading to complement mediated cytotoxicity. In these assays, the patient’s serum may be pre-treated with Dithiothreitol (DTT) to inactivate IgM antibodies and allow for specific detection of IgG antibodies. Following this, very small amounts of purified donor lymphocytes are incubated with the patient’s serum. If the serum contains DSA directed to the donor’s lymphocytes, the antibodies will bind to the cells. When rabbit complement is added, the antigen-antibody complexes will activate the classical complement cascade. This leads to pore formation, breaching the cell membrane of the lymphocytes and causing cell damage and death. Staining with a vital dye will result in entry of the dye into the cells through the pores. The staining can be visualized with an inverted phase-contrast microscope. A standardized scoring system is used to interpret the amount of cytotoxic cell death.