Transplant immuno-diagnostics: crossmatch and antigen detection

Area of Science:

• Transplantation immunology
• Histocompatibility testing
• Immunoserology

Background:

• Donor-specific antibodies (DSAs) are critical in solid organ transplantation, influencing donor selection, matching, and allograft rejection.
• Early assays for anti-human leukocyte antigen (HLA) antibodies were limited by poor sensitivity, specificity, and technical challenges.
• Technological advancements have progressively improved DSA detection, moving from complement-dependent cytotoxicity to cell-based flow cytometry and now solid-phase assays.

Purpose of the Study:

• To review the evolution of technologies for identifying and monitoring donor-directed anti-human leukocyte antigen antibodies.
• To discuss the impact of these antibodies on allograft rejection and survival.
• To highlight current limitations and future directions in DSA testing.

Main Methods:

• Review of historical and current technologies for anti-HLA antibody detection.
• Discussion of assay methodologies including complement-dependent cytotoxicity, flow cytometry, and solid-phase assays.
• Analysis of the clinical significance and challenges in interpreting DSA test results.

Main Results:

• Early whole-cell assays had low sensitivity and specificity.
• Cell-based flow cytometry offered improvements but retained limitations in specificity and sensitivity.
• Solid-phase assays represent a significant advancement, enhancing sensitivity and specificity for low-titer antibodies and previously undetected antigens.

Conclusions:

• Technological progress has dramatically improved the detection of alloantibodies, particularly DSAs.
• Despite advancements, variability in methodology and lack of standardization hinder widespread clinical application.
• Antibody-mediated rejection remains a primary target for improving allograft survival, necessitating continued refinement of DSA monitoring techniques.