CHT Crossmatch Procedures & Interpretation

Question 1

What is the primary purpose of performing a pretransplant crossmatch?

Accepted Answer

To detect preformed donor-specific HLA antibodies in the recipient's serum

Answer

To determine the donor's ABO blood type compatibility

Answer

To assess the recipient's renal function before transplant

Answer

To evaluate donor-recipient body size compatibility

Question 2

In a complement-dependent cytotoxicity (CDC) crossmatch, cell death is assessed by:

Accepted Answer

Exclusion of a vital dye such as eosin Y or trypan blue

Answer

Flow cytometry using fluorescent cell-surface markers

Answer

ELISA optical density readings at 450 nm

Answer

Luminex mean fluorescence intensity (MFI) values

Question 3

A positive T-cell crossmatch using current recipient serum is clinically significant because it indicates:

Accepted Answer

Donor-specific anti-HLA class I antibodies in the recipient

Answer

ABO blood group incompatibility between donor and recipient

Answer

The presence of non-HLA autoantibodies in the recipient

Answer

Recipient sensitization to HLA class II antigens exclusively

Question 4

Dithiothreitol (DTT) treatment of recipient serum before crossmatch testing is used to:

Accepted Answer

Inactivate IgM antibodies by reducing their disulfide bonds

Answer

Enhance complement pathway activation in the assay

Answer

Remove HLA class II antigens from the test mixture

Answer

Increase lymphocyte viability during the incubation period

Question 5

Which best describes an auto-crossmatch and its clinical use?

Accepted Answer

Testing recipient serum against the recipient's own lymphocytes

Answer

Testing recipient serum against cells from a random unrelated donor

Answer

Testing donor serum against recipient lymphocytes in reverse

Answer

Testing archived historical serum against current donor cells

Question 6

The Amos-modified CDC crossmatch improves specificity over the standard CDC by:

Accepted Answer

Including wash steps to remove nonspecific serum components before complement addition

Answer

Adding extra rabbit complement to increase lytic activity

Answer

Substituting human complement for rabbit complement

Answer

Increasing the serum-to-cell ratio in the incubation step

Question 7

Pronase treatment of donor lymphocytes before CDC crossmatch testing enhances sensitivity by:

Accepted Answer

Cleaving complement regulatory proteins (CD55, CD59) from the cell surface

Answer

Removing HLA class I antigens to reduce background reactivity

Answer

Stripping B-cell surface markers such as CD19 and CD20

Answer

Inactivating residual IgG antibody present in the serum