Pre-transplant compatibility testing: Transition from CDCXM to flow cytometry in India

Area of Science:

• Transplantation immunology
• Clinical immunology
• Renal transplantation

Background:

• 40% of kidney transplant candidates are sensitized due to prior alloantigen exposure.
• Donor-specific antibodies (DSAs) detected via pre-transplant compatibility testing are critical for preventing graft rejection.
• Traditional complement-dependent cytotoxicity crossmatch (CDCXM) has limitations in sensitivity.

Purpose of the Study:

• To review the transition from CDCXM to flow cytometry crossmatch (FCXM) in kidney transplantation.
• To highlight the impact of FCXM on pre-transplant testing and clinical decision-making in the Indian context.
• To emphasize FCXM's role in improving graft outcomes by identifying immunologically significant DSAs.

Main Methods:

• Comparison of CDCXM and FCXM methodologies for detecting preformed DSAs.
• Review of studies demonstrating the sensitivity and specificity of FCXM.
• Discussion of modifications to FCXM, such as Halifax and Halifaster protocols.
• Analysis of factors contributing to false-positive and false-negative FCXM results.

Main Results:

• FCXM exhibits superior sensitivity in detecting DSAs compared to CDCXM.
• Positive FCXM results, even with negative CDC-XM, correlate with increased rejection rates and decreased graft survival.
• Streamlined FCXM protocols enhance specificity and speed.
• Despite potential inaccuracies, FCXM is crucial for identifying immunologically significant DSAs.

Conclusions:

• FCXM is the gold standard in modern transplantation immunology for pre-transplant compatibility testing.
• The adoption of FCXM has significantly improved the safety of graft outcomes.
• This review underscores the importance of FCXM in the Indian transplantation landscape for informed clinical decisions.