Background: Sensitization before transplantation and de novo alloantibodies affect a significant population of transplant patients, both portending a poorer prognosis in short- and long-term graft survival. Current approaches to desensitization offer incomplete and impermanent removal of antibody producing cells. In this study, we investigated the kinetics of B cell and alloantibody responses after kidney and skin transplantation in rhesus macaques in order to develop a sustainable preclinical model for evaluating desensitization therapies.

Methods: Nine rhesus macaques underwent unilateral nephrectomy and renal transplantation, with one native kidney preserving normal renal function. Four rhesus macaques underwent skin grafting. No animals received immunosuppression. B cell phenotypes and donor-specific antibody (DSA) production were assessed with polychromatic flow cytometry.

Results: All renal allografts were rejected on day 7-protocol biopsy, and skin grafts at a mean 10.7 ± 3.86 days. DSA kinetics were assessed, revealing a peak DSA level at 44.3 days for kidney and 39.5 days for skin transplant (Fig. A/B, red line indicates mean polynomial fitted curve) and stabilization of DSA by approximately 140 days and 70 days, respectively. Baseline pre-transplant DSA levels were similar for both kidney and skin recipients (p=0.743), but peak levels were significantly higher for kidney-transplanted animals (MFI= 49157.1 vs 6451.3, p=0.005). Immune monitoring revealed a spike in peripheral mature B cells prior to a rise in DSA, with IgG+ (Fig. C, p=0.009 and 0.014 for kidney & skin) significantly increasing and a trend in increase of CD27+ B cells (Fig. D, p= 0.115 and 0.219 for kidney & skin) when normalized for pre-transplant variability.

Conclusions: This study reveals a unique model of investigating sensitization after transplantation. Furthermore, the stabilization of DSA indicates the sustainability of both models in being used for evaluating desensitization techniques. Increasing mature B cell phenotypes preceding the increase in DSA show the possible value of detecting this phenotype change during routine immune monitoring for transplant patients.

« Back to 2013 American Transplant Congress