New Paradigms in Rejection Monitoring: Lymphocyte Subsets as Noninvasive Graft Markers in Vascularized Composite Allotransplantation.

Background: In vascularized composite allotransplantation, face transplantation stands as a transformative intervention for patients with severe facial disfigurement. Monitoring of graft rejection, however, remains a critical challenge. This study aimed to investigate the role of lymphocyte subsets in the early detection and monitoring of graft rejection in face transplantation.

Methods: We conducted a retrospective chart review of 3 face transplant recipients who underwent face transplantation at our institution. Peripheral blood samples were analyzed for lymphocyte subsets at multiple time points posttransplantation. A linear mixed-effects model was used, aiming to identify any upregulation associated with episodes of graft rejection.

Results: A statistically significant relationship was found between clinically treated episodes of rejection, ultimately confirmed by histology, and several lymphocytic subsets. CD3⁺ and CD3⁺CD4⁺ cell lineages were found to be significantly upregulated during times of rejection (P = 0.0147 and P = 0.0153, respectively). Furthermore, CD3⁺CD8⁺ and CD16⁺CD56⁺ cell lineages were also found to be significantly associated with rejection (P = 0.0490 and P = 0.0019, respectively). Further stratification with tacrolimus as a fixed effect demonstrated that CD3⁺, CD3⁺CD4⁺, and CD15⁺CD56⁺ cell lineages remained significantly associated with rejection (P = 0.0167, P = 0.0223, and P = 0.0015, respectively).

Conclusions: Our study demonstrates that monitoring specific lymphocyte subsets offers a promising adjunct for graft surveillance that is less invasive when compared with traditionally used punch biopsies. This approach not only enhances the precision of rejection monitoring but also improves patient comfort and compliance, thereby contributing to better long-term graft outcomes.