Significance Of CD20-positive Lymphocytes Infiltrating In Allograft Renal Biopsies With Chronic Allograft Nephropathy

BackgroundChronic allograft nephropathy (CAN) is the main cause of renal allograft loss. There is a reported prevalence of CAN of 60-70% in protocol biopsies 1 year after transplant. With the increasing number of recipients and the limited donor pool, transplant researchers have shifted their focus toward the underlying mechanisms of CAN in order to develop effective and viable treatments in both clinical and basic areas to improve long-term outcomes.Clinical symptom of CAN manifestations of decreasing kidney function and kidney failure ultimately 3 months after transplantation.It's Characterized by non-specific pathologic is tubular atrophy interstitial fibrosis and glomerular sclerosis. The major clinical manifestations is progressive proteinuria, hypertension and increasing serum creatinine slowly.The etiology of CAN include both immune and non-immune causes. Furthermore, these causes interact to make diagnosis and treatment more complicated. Herein, we use this term to mean active but slowly progressive injury caused by alloreactivity to the graft and further deteriorated by nonimmunologic nonspecific factors. That means the immunologic damage, so-called chronic rejection,provides the allograft a basic background or platform for CAN. Based on this cognition, we focus on immunerelated rather than non-immune-related knowledge in this review. It would be impossible to separate all the individual parts of the mechanisms and strategies due to their overlap; instead, we try to follow the entire process of the immune response to elucidate the mechanisms, with an emphasis on new clinical and experimental strategies.In recent years there has been increasing recognition of the importance of acute antibody-mediated renal allograft rejection owing in part to four factors. First, there has been a dramatic improvement in the technology of antibody detection.Newer assays incorporating purified HLA antigens bound to solid phase substrates permit identification of previously undetectable levels of donor-specific antibodies with accuracy unobtainable using donor-cell-based assays. Secondly, the histologic appearance of acute antibody-mediated rejection has been more clearly delineated, following the recognition of the importance of the complement degradation factor C4d as a histologic marker. Third, protocols incorporating pre-and posttransplant plasmapheresis have shown the feasibility of antibody incompatible transplantation in the setting of ABO blood group mismatch, with satisfactory outcome. Finally,owing primarily to the dilemma posed by allosensitized candidates whose wide array of anti-HLA antibodies severely restricts their transplantability using traditional approaches, new protocols have been developed, which permit antibody incompatible kidney transplantation. These transplants, although often successful, have an increased risk of implications. At present, the research of humoral immunity emphasis on the AR, but little on long-term survival and the CAN.CAN clinical decision-making is based on the biopsy on the Banff classification.However, Small or non-specific cell infiltration in renal biopsy is not clear in Banff classification and their interpretation, In which B lymphocyte infiltration is common.The expression of CD20, a cell-surface marker specific to B lymphocytes, start on pro-B lymphocyte, till on mature B lymphocyte, end on plasm cells. B lymphocyte play multiple roles in the immune response,receiving antigen stimulation, activation and proliferation of mature plasma cells, secretion of antibody-mediated humoral rejection,as well as uptakting, processing and presenting antigens to stimulate T lymphocyte activation and involved in cellular rejection as Antigen-presenting cells,such as intra-articular T cells in rheumatoid arthritis activated by synovial fluid CD20-positive lymphocytes in peripheral lymphoid follicles.but the mechanism research about CD20-positive lymphocytes on transplantation immunity is little.The current study about CD20 lymphocyte is focused on acute cellular rejection,Subsequent studies have provided support for the association between CD20-positive B cell infiltrates and refractory rejection or poor graft outcomes. Anti-CD20 monoclonal antibody have applicated in clinical for steroid-resistant acute rejection,but little study about CD20-positive B cell infiltrates in CAN,which effects most of graft outcomes.ObjectiveInvestigate the action mechanism of CD20 lymphocyte infiltration in the allograft biopsy CAN and the long-term survival combined C4d, circulating antibodies PRA and othermarks of humoral immunity. The study will support evidence for strengthening immunesuppressive on B cells and marks for diagnosis.Object and methods:1.44 cases have indications to renal biopsy and confirmed CAN 2 years after kidney transplantation.were Collected,and followed at least 1 year.The information about HLA matches,PRA, immunosuppression,serum creatinine level,acute rejection were recorded.2. Result of pathology,First pathological grading, CD20 expression and C4d was examined by Immunohistochemistry technique. Around more than 25% in the neighboring tubular capillaries with C4d deposition judged to be positive.Transplant renal interstitial diffuse, strong, and aggregation of dye was defined as the positive expression of CD20 (≥300 cells/hpf)3. PRA testing.5ml whole blood in patients was detected by ELISA.4.According to the following, PRA change, serum creatinine level,and graft survival were recorded.5.Statistical analysis:SPSS13.0 statistical software was used.The measurement data was showed was Mean±standard deviation, the measurement data was tested by independent-samples t-test, numeration data was tested by crosstabs.p<0.05 was dedined as statistical significance.ResultsAll the case were followed at least 1 year,end point of follow is allograft disfunction or the patients death.No patient was dead or lost and allograft disfunction in the follow period.1.44 cases were involved in the study, male 24, female 20.Age range 21 to 69 years old, The average age of 38.5±7.6 years. Body weight range of 42～68kg, average weight 52.5±6.6kg. Biopsy time is 5-24 months after renal transplantation, average of 15.3±4.9 months.35 cases cadaveric, relatives live donor 9 cases.0 mismatch 5 cases,1 mismatch 8 cases,2 mismatch 13 cases,3 mismatch 13 cases,4 mismatch 6 cases.immunosuppression agent basaed on ciclosporin is 14 cases, prograf 30 cases, prograf combined with WZ capsule 16 cases among it,no combined 14 cases.immune induction treatment 14 cases,Delayed graft function 7cases.All the specimen were pathology tested in accordance with Banff05.CAN Grade Ⅰ19 cases (43.2%),Ⅱ16 cases (43.2%),Ⅲ9 cases (43.2%), There was no difference between ciclosporin group and prograf group among CAN classification, Combined with WZ capsule group and non-combined too among prograf group.2.13 cases(29.5%) was detected CD20-positive lymphocytes,31cases (70.5%) negative. CD20-positive lymphocytes in biopsy showed nodular and scattered of infiltration. The positive rate have no statistic difference among gender,age,weight, HLA match,donor type, immunosuppression agent, immune induction treatment and DGF.There were CANⅠ5 cases (26.3%),Ⅱ4 cases (25.0%),Ⅲ4 cases (44.4%) in CD20-positive group,no statistic difference among the three group.There were no statstic significance between the only CAN group and CAN with AR group in CD20-positive rate.3.Immunohistochemical staining show 12 cases (27.3%) with C4d linear deposition in peritubular capillary endothelial cells (PTC) CAN cases, C4d positive rate have no significant difference among the CAN classification. The relationship between C4d deposition and CD20-positive lymphocytic infiltration have no statistic significant.4.CD20-positive rate was significant higher in PRA positive group than negative group (71.4% vs21.6%),The average serum creatinine of CD20-negtive group and CD20-posigtive group is 140.8±22.0μmol/L and 183.5.4±25.5μmol/L before biopsy, 165.6±37.6μmol/L and 242.2±59.1μmol/L 1 year after biopsy. The average serum creatinine of CD20-positive group is higher than and CD20-negtive group before biopsy, after biopsy too. The average serum creatinine of C4d negtive group and C4d positive group is 186.1±55.1μmol/L and 193.9±62.7μmol/L before biopsy, 154.7±29.3μmol/L and 149.9±33.6μmol/L L 1 year after biopsy. The average serum creatinine of CD20-positive group and CD20-negtive group have no statistic difference in before biopsy snd after biopsy. Conclusions1.Basic Immunosuppression agents have no relationship with CAN classification. Combined with WZ capsule have no correlation with CAN classification in prograf group. The concentration enhanced by WZ capsules is effective.2.Progresive chronic humoral immune response is a high risk in the process of CAN.3.No CD20- positive cells were detected in normal renal tissue, the number of cells in rejecting cases and in CAN was significantly higher, particularly among cases of acute rejection. The CD20-positive lymphocyte infiltration have no relationship with CAN classification and C4d deposition in PTC,but were associated with circulating antibody PRA and allograft long-term outcome. Pathogenetic mechanism may not contribute to chronic humoral immune,but B cells presenting donor antigens, recognized and activated by T cell as antigen-presenting cells.4.CD20 infiltrating in renal allografts associated with poor outcome.It's may have significance in diagnosis and provide a rationale for further clinical trials of B cell depletion therapy.