Crossmatch Procedures & Interpretation Flashcards
7 cards from real CHT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Crossmatch Procedures & Interpretation flashcards as text
What is the primary purpose of performing a pretransplant crossmatch?
Answer: To detect preformed donor-specific HLA antibodies in the recipient's serum
The pretransplant crossmatch detects preformed donor-specific antibodies (DSAs) in the recipient that could cause hyperacute rejection upon transplantation.
In a complement-dependent cytotoxicity (CDC) crossmatch, cell death is assessed by:
Answer: Exclusion of a vital dye such as eosin Y or trypan blue
CDC crossmatch uses vital dye exclusion — dead cells with compromised membranes take up the dye, allowing percent cytotoxicity to be calculated.
A positive T-cell crossmatch using current recipient serum is clinically significant because it indicates:
Answer: Donor-specific anti-HLA class I antibodies in the recipient
T cells express HLA class I antigens (A, B, C), so a positive T-cell crossmatch indicates the recipient has preformed antibodies against donor HLA class I antigens.
Dithiothreitol (DTT) treatment of recipient serum before crossmatch testing is used to:
Answer: Inactivate IgM antibodies by reducing their disulfide bonds
DTT cleaves the disulfide bonds that hold the pentameric IgM structure together, selectively inactivating IgM and allowing identification of IgG-mediated crossmatch reactivity.
Which best describes an auto-crossmatch and its clinical use?
Answer: Testing recipient serum against the recipient's own lymphocytes
An auto-crossmatch tests recipient serum against the recipient's own cells to detect autoantibodies, which can cause false-positive crossmatch results if not identified.
The Amos-modified CDC crossmatch improves specificity over the standard CDC by:
Answer: Including wash steps to remove nonspecific serum components before complement addition
Washing steps in the Amos-modified CDC remove unbound antibodies and serum proteins that may activate complement nonspecifically, reducing false-positive results.
Pronase treatment of donor lymphocytes before CDC crossmatch testing enhances sensitivity by:
Answer: Cleaving complement regulatory proteins (CD55, CD59) from the cell surface
Pronase is a protease that removes complement inhibitory proteins (CD55/DAF and CD59/protectin) from the cell surface, making cells more susceptible to complement-mediated lysis.