Antibody Detection & Characterization Flashcards
6 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 6 Antibody Detection & Characterization flashcards as text
What is 'epitope analysis' in the context of HLA antibody characterization?
Answer: Identifying the specific molecular surface features (epitopes/eplets) on HLA antigens targeted by antibodies
Epitope analysis uses tools like HLAMatchmaker to identify the specific polymorphic amino acid configurations (eplets) on HLA molecules that are targeted by the patient's antibodies.
When a Luminex SAB assay shows high MFI on beads from one manufacturer but not another for the same antigen, what is the likely explanation?
Answer: Bead-specific artifacts such as denatured HLA antigen or different antigen density between manufacturers
Discrepancies between platforms often reflect bead-specific artifacts including denatured or cryptic antigens on some beads, highlighting the need for confirmatory testing.
Which test can confirm the clinical relevance of DSA detected by SAB assay by evaluating actual cell lysis in the presence of complement?
Answer: CDC crossmatch
The CDC crossmatch uses the patient's serum with donor lymphocytes and complement; cell death confirms the antibody can activate complement and is functionally significant.
What does 'acceptable mismatch' mean in the context of sensitized patients awaiting transplant?
Answer: HLA mismatches against which the patient has NO antibodies and therefore carries minimal immunological risk
Acceptable mismatches are donor HLA antigens against which the specific recipient has no detectable antibodies, allowing transplantation across those mismatches without crossmatch risk.
What is the 'Luminex bead C1q assay' used to assess?
Answer: Whether HLA antibodies can fix complement (C1q) and are therefore more likely to cause AMR
The C1q SAB assay adds C1q to the standard SAB test to identify which HLA antibodies are capable of fixing complement, stratifying DSA by functional risk.
Which of the following best describes 'cross-reactive groups' (CREGs) in HLA antibody analysis?
Answer: Groups of HLA antigens sharing common epitopes that may be targeted by the same antibody
CREGs are sets of HLA antigens that share public epitopes, meaning an antibody to one antigen may cross-react with all antigens in the group due to shared molecular features.