Discriminating Post-Transplant Rejection from Infection by Detecting TCR-CD3 Oligomerization on Extracellular...

Area of Science:

• Immunology
• Biomarker Discovery
• Transplant Medicine

Background:

• Post-transplant rejection and infection are major threats to long-term survival.
• Current diagnostic methods lack standardization for simultaneous risk assessment of rejection and infection.

Purpose of the Study:

• To develop and validate a novel assay for distinguishing acute cellular rejection from infection in transplant recipients.
• To identify T cell receptor (TCR)-CD3 oligomers on extracellular vesicles (EVs) as a potential biomarker.

Main Methods:

• Development of a caliper-shaped aptamer probe to quantify the ratio of TCR-CD3 oligomeric to monomeric EVs from CD8+ cytotoxic T cells.
• Validation in murine models and a clinical cohort of 34 transplant recipients.
• Assessment of assay performance using fluorescence ratios, sensitivity, specificity, and area under the curve (AUC).

Main Results:

• The assay showed higher fluorescence ratios in mice with allograft rejection compared to infection (0.26 vs 0.14).
• In clinical samples, the assay distinguished rejection from infection, even with overlapping symptoms, and identified rejection in coinfected patients.
• The assay achieved an AUC of 0.85, with 71% sensitivity and 90% specificity at a cutoff of 0.69.

Conclusions:

• Extracellular vesicle (EV)-based TCR-CD3 oligomer quantification is a robust and minimally invasive biomarker for acute cellular rejection.
• This assay can differentiate rejection from infection, aiding in clinical decision-making.
• The tool has the potential to guide immunosuppressive therapy and decrease reliance on invasive biopsies.