Immuno-Labeled Treg, T-Cells and Their Ratios Predict the Immunosuppression Therapy Effectiveness in Liver Allograft Recipients
Anmaar Abdul-Nabi, Josh Levitsky, Haonan Li, Wanying Zhang, Sambasiva Rao, Guang-Yu Yang. Northwestern University, Chicago, IL
Background: Complete immunosuppression withdrawal (i.e., operational tolerance) has been possible in only ∼ 20% of liver transplant recipients (LT). Identification of specific T cell populations responsible for immunoregulation may give clues toward achieving tolerance in LT. Previous reports have demonstrated differences in the effects of calcineurin and mTOR inhibitors (sirolimus) on Tregs and T cell populations. We present a prospective study and extensive analysis of morphology of Treg (FOXP3+), CD3, CD4, and CD8 T cell populations in liver biopsies from 20 LT recipients before and after conversion from calcineurin inhibitors to sirolimus monotherapy. This would support larger scale studies utilizing sirolimus conversion as an intermediate step toward more clinically successsful immunosuppression withdrawal in LT.
Design: In 20 liver allograft recipients, a 2-cm core liver biopsy was obtained, once before and once 6 months after the conversion to the sirolimus monotherapy. Hematoxylin and eosin, tri-chrome, and immunohistochemistry (IHC) was performed using antibodies to FOXP3 (Treg), CD3, CD4, and CD8. The number of CD3, FOXP3, CD4 and CD8 positive lymphocytes per high power field were counted. Ratios of FOXP3:CD3 and CD4:CD8 were calculated, and an average of three portal-tract ratios was recorded. 5 documented rejection cases were used for comparison.
Results: The Tregs presented mostly as single cells scattered throughout the portal area with occasional clustering in the biopsies before conversion to sirolimus monotherapy. Semi-quantitative analysis revealed that the Tregs were significantly increased after six months of conversion to sirolimus monotherapy in comparison to the rest of the T cells with the ratio of FOXP3:CD3 positive cells being (0.19 ± 0.1), compared to beginning of the therapy (0.11 ± 0.1; P = 0.01) or rejection cases (0.09 ± 0.01; P = 0.005). In addition, the ratio of CD4:CD8-positive cells also increased significantly (1.2 ± 0.5), compared to beginning of the therapy (0.86 ± 0.2; P = 0.02) or those with rejection (0.9 ± 0.1; P = 0.01), consistent with the increased number of the Tregs. The vast majority of T cells in the rejection cases are composed of CD8+ T cells with very rare FOXP3 + and CD4+ cells.
Conclusions: T cells immunophenotyping by IHC in liver core biopsies of liver allograft recipients is a practical and reliable method of prediction the effectiveness of immunosuppression therapy, particularly conversion to sirolimus monotherapy. Also the T cells immunophenotype characterization will help in detecting early rejection cases.
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 148, Tuesday Afternoon