IMMUNOLOGICAL PREDICTORS OF RENAL GRAFT REJECTION IN THE EARLY POSTOPERATIVE PERIOD

Objective. To determine the immunological predictors of renal graft rejection in the early postoperative period. Methods. Three groups were formed out of the 197 renal graft recipients. The group PGF (n=101) was made up of patients with satisfactory primary graft function. The group PGD (n = 82) included patients with primary graft dysfunction without episodes of rejection. The group RGR (n=14) consisted of patients with primary dysfunction and renal graft rejection. On the 7^th day after transplantation the early kidney graft function was assessed on the basis ofserum creatinine levels. When the serum creatinine value was lower than 300 μmol/L the function was considered to be primary, at a creatinine concentration was equal to or higher than 300 μmol/L, as well as in the case of needfor maintenance dialysis on the first week after transplantation, the state was classified as the renal graft dysfunction. In the early postoperative period, the number of LIN-HLA-DR+ dendritic cells with the LIN-HLA-DR+CD11c+CD123- and LIN-HLA-DR+CD11c-CD123+ phenotypes in the fluid from the drainage installed to the kidney graft during surgery was determined. Predictive characteristics of the mDC and pDC levels in the drainage fluid were determined to predict renal graft rejection, and diagnostic capability of this indicator were identified. Results. It has been revealed that renal graft rejection is characterized by a significant growth of the total number of dendritic cells in the drainage fluid, mainly due to myeloid ones. Predictive characteristics were determined by the level of myeloid and plasmacytoid dendritic cells in the drainage fluid. The cut-off point of the level of myeloid dendritic cells was determined at the level of 60.32%, and for plasmacytoid dendritic cells it corresponded to 39.68%. Conclusion. With the level of myeloid dendritic cells in the drainage fluid greater or equal 60.32%, and plasmacytoid cells lower or equal 39.68%, renal graft rejection is predicted with a sensitivity of 99% and 93%, respectively, and a specificity of 89% and 91%, respectively. What this paper adds The level of dendritic cells and their subpopulations in the drainage fluid in renal graft recipients has been firstly studied. It has been established that acute renal graft rejection is associated with a high concentration of the total number of dendritic cells in the drainage fluid. More over this increase occurs mainly due to myeloid dendritic cells. The determination of the level of myeloid and plasmacytoid dendritic cells in the drainage fluid can be used as a predictor of renal graft rejection.

MO937ASSOCIATION OF RENAL ELASTOGRAPHY WITH BANFF MICROVASCULAR INFLAMMATION IN PROTOCOL BIOPSIES FOR SUBCLINICAL RENAL GRAFT REJECTION DIAGNOSIS

Background and Aims The most common cause of renal graft failure is chronic dysfunction in 24.7% and the most common etiology of this is clinical or subclinical rejection. The incidence of subclinical rejection varies from 15 to 50% (25% in protocol biopsies in the first year after transplantation and 35% after two years). Melek E et al have shown that doppler ultrasound is a non-invasive study that, through the resistance index (RI), has traditionally been used for the early diagnosis of acute graft rejection (AR); however, it is influenced by extrarenal systemic factors. Naesens et al published that in 321 kidney transplant recipients, RI wasn´t associated with histological findings of AR in protocol biopsies. Elastography is another ultrasonographic modality for the evaluation of the kidney graft, which measures the stiffness/elasticity of the tissue expressed in Kpa (kilopascals). Stock in 2011 and Kim BJ in 2018 published studies where they showed that increased stiffness was correlated with the diagnosis of kidney graft rejection. The aim of this study was to describe the association between elastography with microvascular inflammation determined by Banff for diagnosis of renal allograft subclinical rejection. Method Observational, analytical and cross-sectional study that included kidney transplant patients who underwent protocol biopsy and renal elastography at the Central Military Hospital in Mexico City between January 2018 and December 2020. The demographic and biochemical characteristics, degree elastography stiffness and Banff 2017 lesions were determined. The sample calculation, determination of correlation degree and ROC curve elaboration were performed. Results We included 146 patients. 56.8% were men; the most common causes of CKD were undetermined and chronic glomerulonephritis with 52.7% and 17.1% respectively. 47.3% were hypertensive at biopsy time and 1.4% had chronic heart failure. The most common immunosuppression schemes were FK/MPA/steroid and FK/mTOR-i/steroid with 60.3% and 13%, respectively. The mean GFR was 65.31 ml/min which shows graft good function. The mean stiffness in the elastography was 15.73 Kpa. The rest of baseline data are shown in Table 1. Had rejection 36.3% of the biopsies, the most frequent chronic AMR C4d- with 15.1% and active AMR C4d- 8.9%. When analyzing the ROC curves, the Banff 2017 lesions AUC values that correlated better with graft stiffness were: v=0.607, i=0.594, g=0.578, C4d deposit=0.519, ptc=0.498. Figure 1. Conclusion Intimal arteritis, inflammation, and glomerulitis are the Banff lesions best associated with elastography graft stiffness in protocol biopsies. Prospective studies are recommended in patients with acute graft dysfunction to find an adequate elastography cut-off value that allows another tool for fast and non-invasive diagnosis of renal graft rejection.