Functional assessment of immune markers of graft rejection: a comprehensive study in live‐related donor renal transplantation

Abstract

A better understanding of the immunobiological processes and predictors of graft rejection holds promise for the development of potential therapeutic strategies and also individualization of immunosuppression. The objective of this study is to analyze the clinical relevance of immune parameters such as antidonor antihuman leukocyte antigen (anti-HLA) antibodies, monitoring of cytokines and their receptors on the graft outcome following live-related donor renal transplantation. Flow cytometry-based methods were used to detect antidonor antibodies (flow cytometry crossmatch, FCXM) and intracellular cytokines. Enzyme-linked immunosorbent assay (ELISA) methods were employed to detect anti-HLA class I and class II antibodies and quantitative serum-soluble interleukin-2 receptor (sIL-2R) levels. The data revealed that patients with HLA class I-specific IgG antibody experienced higher acute rejection (AR) episodes at 1 yr in comparison to the antibody negative group (82% vs. 56%, p = 0.01). On the contrary, donor-specific class II antibodies (B+) did not have any influence on the graft survival. However, 15 recipients having both T- and B-cell antidonor antibodies (T+B+) had significantly poor graft survival (60%) as compared to the antibody-negative group (T-B-, 82%, p = 0.05). Additionally, patients having non-donor but HLA-specific antibodies (FCXM-/ELISA+) had poor graft survival as compared to the antibody-negative group (64% vs. 88%, p < 0.05). Further, patients undergoing AR episodes had significantly higher expression of IFN-gamma-producing T cells (19.16 +/- 7.4% median 17.50) as compared to their pre-transplant levels (5.68 +/- 1.63%, Median 5.20) and the non-rejecter group (5.97 +/- 4.39%, median 4.3, p = 0.0004). Similarly sIL-2 was significantly increased in AR episodes during the first month of transplantation (292 +/- 131.5 pmol/L) as compared to those with well-functioning grafts (p = 0.01) and healthy controls (p = 0.001). Evaluation of antidonor antibodies by flow cytometry is found to be relatively more sensitive and a better predictor of graft outcome. Further monitoring of cytokine expression profile of primed peripheral T-helper cells and quantitative analysis of sIL-2R offer additional valuable diagnostic and prognostic tools for follow-up of transplant subjects and a better alternative for functional assessment of immunosuppression.