Immuno-histological assessment of sub-clinical acute and borderline rejection in renal allograft recipients: Data from a transplant center in India

This single-center study was carried out on living related and unrelated renal transplant recipients (RTRs) to evaluate the usefulness of surveillance biopsies in monitoring stable renal allografts using immuno-histological markers for immune-activation. This is a prospective, longitudinal study. Protocol biopsies of 60 RTRs with stable graft function were evaluated at three, six and 12 months post-transplant. Immuno-histological evaluation was carried out using immune-activation markers (perforins, granzyme and interleukin-2R), phenotypic markers (CD-3 and CD-20), viral markers and C4d. The demographic and clinical profile was recorded for each patient. All cases of acute sub-clinical rejection (SCR) were treated and borderline SCR cases were followed-up without treatment. SCR at three and six months post-transplant was evident in 16.7% and 3.7% of RTRs, respectively. Positive statistical association of SCR was seen with HLA-DR mismatches, whereas patients receiving induction therapy and tacrolimus-based immunosuppression exhibited a lower incidence of SCR. T cell phenotype with persistent expression of immune-activation markers exhibited positive statistical association with interstitial fibrosis and tubular atrophy at 12-month follow-up biopsy. The mean creatinine levels were significantly lower in the protocol biopsy group than the non-protocol biopsy group. No significant difference was found between the mean creatinine levels of the SCR group after treatment and the non-SCR cases within the protocol biopsy group. Early treatment of sub-clinical acute rejection leads to better functional outcomes. However, persistent immune-activation is associated with chronicity and may have implications on long-term graft survival.