CHT Antibody Detection & Characterization 2

Question 1

Non-HLA antibodies have been implicated in transplant rejection. Which non-HLA target is most studied?

Accepted Answer

MICA (MHC class I chain-related antigen A)

Answer

MICA is a stress-induced cell surface molecule encoded in the MHC region; anti-MICA antibodies have been associated with rejection and graft loss independent of HLA.

Question 2

Which immunoglobulin subclass of IgG most efficiently activates complement and is most associated with acute AMR?

Accepted Answer

IgG1 and IgG3

Answer

IgG1 and IgG3 are the most potent complement-activating IgG subclasses and are strongly associated with antibody-mediated rejection.

Question 3

What does it mean when DSA is described as 'complement-binding' in the clinical context?

Accepted Answer

The antibody can activate the classical complement cascade, increasing rejection risk

Answer

Complement-binding DSA (e.g., C1q-binding or C3d-fixing) indicates the antibody can activate complement, which is associated with more severe AMR and worse graft outcomes.

Question 4

In Luminex-based crossmatch (LCM/FCXM by bead), what advantage does it have over traditional CDC crossmatch?

Accepted Answer

Higher sensitivity for detecting low-level HLA antibodies

Answer

Luminex and flow cytometric crossmatches are significantly more sensitive than CDC, detecting antibody levels too low to activate complement but still potentially harmful.

Question 5

What is the purpose of DTT (dithiothreitol) treatment of serum in HLA antibody testing?

Accepted Answer

Inactivates IgM antibodies by breaking disulfide bonds to allow IgG-only testing

Answer

DTT cleaves the disulfide bonds that hold IgM pentamers together, inactivating IgM antibodies so the assay result reflects only IgG antibodies.

CHT - Certified Histocompatibility Technologist Practice Test

CHT - Certified Histocompatibility Technologist Practice Test

CHT Antibody Detection & Characterization 2