CHT Crossmatch Procedures & Interpretation 3

Question 1

A donor-specific antibody (DSA) detected by single antigen bead assay with an MFI of approximately 3,000-5,000 would most likely produce which crossmatch results?

Accepted Answer

Negative CDC crossmatch but positive flow cytometric crossmatch

Answer

Negative CDC crossmatch and negative flow cytometric crossmatch

Answer

Positive CDC crossmatch and positive flow cytometric crossmatch

Answer

Positive CDC crossmatch but negative flow cytometric crossmatch

Question 2

A historical (peak) crossmatch uses archived recipient serum to:

Accepted Answer

Detect prior sensitization events that may no longer be reflected in current serum

Answer

Test preserved donor cells stored for more than one year post-procurement

Answer

Perform a reverse crossmatch of donor serum against recipient lymphocytes

Answer

Screen against a panel of random volunteer donors

Question 3

On the standard NIH CDC scoring scale, a score of 8 indicates:

Accepted Answer

81–100% cytotoxicity (strongly positive result)

Answer

0–10% cytotoxicity (negative result)

Answer

11–20% cytotoxicity (borderline result)

Answer

51–80% cytotoxicity (positive result)

Question 4

Which crossmatch technique has the LEAST sensitivity for detecting donor-specific antibodies?

Accepted Answer

Standard CDC crossmatch without wash steps

Answer

Flow cytometric crossmatch (FCXM)

Answer

AHG-enhanced CDC crossmatch

Answer

Luminex single antigen bead (SAB) assay

Question 5

In a standard CDC crossmatch protocol, which source of complement is most commonly used?

Accepted Answer

Exogenous rabbit serum added as an external complement source

Answer

Endogenous complement already present in the recipient's test serum

Answer

Purified human C3 and C4 components reconstituted from lyophilized stock

Answer

Complement synthesized by the donor lymphocytes during incubation

Question 6

Chloroquine diphosphate treatment of donor cells before crossmatch testing is primarily used to:

Accepted Answer

Strip HLA class II antigens from the cell surface to reduce B-cell crossmatch sensitivity

Answer

Remove IgG antibodies nonspecifically adsorbed to the cell surface

Answer

Enhance complement receptor expression on lymphocytes

Answer

Inactivate non-HLA antibodies present in the recipient serum

Question 7

In the context of a living donor kidney transplant, a positive T-cell CDC crossmatch using current recipient serum most commonly leads to:

Accepted Answer

Avoidance of transplantation or initiation of a desensitization protocol

Answer

Proceeding with transplantation under standard triple-drug immunosuppression

Answer

Delaying repeat crossmatch testing for six months

Answer

Proceeding with transplantation but using only B-cell crossmatch results for decision-making