Frequency of Human Leukocyte Antigens and Donor Specific Antibodies in Long-Term Living Donor Kidney Transplantation

PurposeHLA antibodies have been shown to be associated with late graft loss. In this study, we defined the incidence and profiles of anti-HLA antibodies and their impact on graft outcome in long-term kidney recipients.MethodsThe sera of 118 kidney transplant recipients were screened for anti-HLA antibody presence. The antigen specificity of the detected HLA class I and class II antibodies was identified using a Luminex assay (Luminex Corp, Austin, TX, United States). Presence of donor specific antibodies (DSA) was examined in individuals with anti-HLA antibodies using the Luminex method.ResultsAnti-HLA class I and/or class II antibodies were detected in serum of 16.1% of the kidney transplant patients. The antibodies were directed against HLA class I antigens in 4 patients (21.1%), HLA class II antigens in 9 patients (47.4%), and both class I and class II antigens in 6 patients (31.6%). The overall prevalence of DSA was 10.2%. Anti-HLA antibodies were significantly associated with higher rate of cyclosporine use. Presence of DSA was associated with a lower rate of tacrolimus use, a higher rate of cyclosporine use, and lower donor age. Presence of anti-HLA antibodies was associated with higher acute cellular rejection and higher chronic active humoral rejection rates. Presence of DSA was associated with chronic active humoral rejection.ConclusionThe presence of either HLA antibodies or DSA significantly correlated with lower graft survival, poor transplant function, and proteinuria.     

Prevalence and significance of anti-HLA and donor-specific antibodies long-term after renal transplantation

Post-transplant circulating anti-human leukocyte antigens (HLA)-antibodies and C4d in allograft biopsies may be important in chronic rejection in renal transplant recipients (RTR). We determined the prevalence and significance of anti-HLA-antibodies and donor-specific antibodies (DSA). Sera were collected from 251 RTR >6 months post-transplant. Sera were tested using enzyme-linked immunosorbent assay (ELISA) screening for anti-HLA antibodies. Positive sera were retested with ELISA-specific panel for antibody specificity. A 11.2% of patients had anti-HLA antibodies and 4.4% had DSA. Anti-HLA antibodies were significantly associated with pretransplant sensitization, acute rejection and in multivariate analysis, higher serum creatinine (2.15 +/- 0.98 vs. 1.57 +/- 0.69 mg/dl in negative anti-HLA antibodies group). Allograft biopsies performed in a subset of patients with anti-HLA antibodies revealed that 66% had C4d in peritubular capillaries (0% in patients without antibodies). Anti-HLA antibodies were associated with a worse allograft function and in situ evidence of anti-donor humoral alloreactivity. Long-term RTR with an increase in creatinine could be screened for anti-HLA antibodies and C4d in biopsy.     

Therapy with plasmapheresis and intravenous immunoglobulin for acute humoral rejection in kidney transplantation

BACKGROUND: Acute humoral rejection (AHR) is characterized by acute graft dysfunction associated with de novo production of donor-specific alloantibodies (DSA) and C4d deposition in peritubular capillaries of the renal allograft. It has been reported the combination of plasmapheresis (PP) and intravenous gamma globulin (IVIG) as effective rescue therapy for established AHR. METHODS: Between 1999 and 2004, seven kidney allografts recipients suffered from AHR diagnosed by severe rejection and C4d staining in peritubular capillaries. All patients had a negative cross-match before renal transplantation. RESULTS: All patients were treated with daily sessions of PP and in four cases IVIG was added after the last PP session. Tacrolimus and mycophenolate mofetil were employed as maintenance immunosuppressive regimen. In one case, rituximab was added to PP and IVIG owing to refractory humoral rejection. At 1 year, patient survival was 100%, allograft survival was 70%, and the mean serum creatinine was 201 micromol/L. CONCLUSIONS: AHR is a severe form of rejection associated with a poor prognosis, but its early diagnosis and treatment with PP and IVIG allows reversal of AHR reaching a 70% graft survival at 1 year.     

Prevalence of donor-specific anti-HLA antibodies during episodes of renal allograft rejection

BACKGROUND: Recent studies suggest that the appearance of anti-HLA antibodies in the early posttransplant period is associated with an increased incidence of acute and chronic rejection months later. However, very little is known about the prevalence of anti-HLA antibodies at the time that the rejection episodes are diagnosed. The purpose of this study was to analyze retrospectively 420 sera from 263 renal allograft recipients who were readmitted to the hospital for any reason between 1989 and 1998 in order to determine if a correlation existed between the presence of donor-specific anti-HLA antibodies and graft rejection. METHODS: Sera were assayed for IgG HLA class I and II antibodies by ELISA. The ELISA results were analyzed using contingency tables with Fisher's exact test and compared with mismatched antigens in the donor. RESULTS: Antibodies to donor HLA class I molecules in the posttransplant sera were extremely rare, occurring in only 6 of the 420 sera (1.4%) analyzed. Antibodies to donor class II antigens were slightly more common, occurring in 25 of the 420 sera (6%). In 21 of these 25 cases (84%), the presence of donor-specific HLA class II antibodies was associated with episodes of either acute (n=14) or chronic rejection (n=7). Five patients had antibodies to both class I and class II donor antigens, and all five of them lost their grafts to rejection. CONCLUSION: Although the presence of donor-specific HLA antibodies presented a significant risk for acute or chronic rejection, 77% of all acute and chronic rejections occurred in patients without detectable HLA antibodies.     

Plasmapheresis and intravenous immune globulin provides effective rescue therapy for refractory humoral rejection and allows kidneys to be successfully transplanted into cross-match-positive recipients

BACKGROUND: Hyperacute rejection (HAR) and acute humoral rejection (AHR) remain recalcitrant conditions without effective treatments, and usually result in graft loss. Plasmapheresis (PP) has been shown to remove HLA- specific antibody (Ab) in many different clinical settings. Intravenous gamma globulin (IVIG) has been used to suppress alloantibody and modulate immune responses. Our hypothesis was that a combination of PP and IVIG could effectively and durably remove donor-specific, anti-HLA antibody (Ab), rescuing patients with established AHR and preemptively desensitizing recipients who had positive crossmatches with a potential live donor. METHODS: The study patients consisted of seven live donor kidney transplant recipients who experienced AHR and had donor-specific Ab (DSA) for one or more mismatched donor HLA antigens. The patients segregated into two groups: three patients were treated for established AHR (rescue group) and four cross-match-positive patients received therapy before transplantation (preemptive group). RESULTS: Using PP/IVIG we have successfully reversed established AHR in three patients. Four patients who were cross-match-positive (3 by flow cytometry and 1 by cytotoxic assay) and had DSA before treatment underwent successful renal transplantation utilizing their live donor. The overall mean creatinine for both treatment groups is 1.4+/-0.8 with a mean follow up of 58+/-40 weeks (range 17-116 weeks). CONCLUSIONS: In this study, we present seven patients for whom the combined therapies of PP/IVIG were successful in reversing AHR mediated by Ab specific for donor HLA antigens. Furthermore, this protocol shows promise for eliminating DSA preemptively among patients with low-titer positive antihuman globulin-enhanced, complement-dependent cytotoxicity (AHG-CDC) cross-matches, allowing the successful transplantation of these patients using a live donor without any cases of HAR.     

Diagnosis and treatment of acute humoral rejection after kidney transplantation: preliminary experience

BACKGROUND: Acute humoral rejection, or rejection associated with de novo production of anti-HLA donor-specific antibodies (DSA) after kidney transplantation (KTx), is a clinicopathologic entity that is not completely understood. Recent studies have proposed criteria for its diagnosis, including: (1) steroid-resistant acute dysfunction; (2) positive post-Tx donor-specific crossmatch (XM); and (3) widespread C4d deposits in peritubular capillaries (PTC) upon renal biopsy. METHODS: During 2002, prospective screening for AHR was established at our unit, seeking DSA post-KTx in selected cases of steroid-resistant acute rejection or acute dysfunction in high-risk sensitized or re-Tx patients. Frozen donor lymphocytes were used for post-Tx flow cytometry (FC) XM and high-definition flow PRA for patients with no frozen donor cells. We treated patients diagnosed with DSA using plasma exchange and polyclonal immunoglobulin. RESULTS: Post-Tx DSA studies were performed in 9 of 94 patients transplanted during 2002. We detected DSA post-Tx in 3 of 9 recipients: 2 by FCXM and 1 using high-definition flow PRA. Two were highly sensitized pre-Tx, but the third patient was a 70-year-old woman receiving a first Tx (PRA=0%). All 3 recipients presented with severe steroid-resistant acute renal dysfunction during the first 2 weeks post-Tx. Biopsies showed some features of AHR (neutrophils in PTC); 1 case showed no signs of concomitant cellular rejection. All rejection episodes were treated successfully (XM became negative and renal function recovered) by combining plasma exchange and polyclonal immunoglobulin. CONCLUSIONS: The use of specific tools, like the crossmatch, in cases of acute, steroid-resistant renal graft dysfunction is important to identify and treat otherwise undetected humoral mechanisms of rejection.     

Renal Transplantation in Patients With Pre-Transplant Donor-Specific Antibodies and Negative Flow Cytometry Crossmatches

The clinical significance of pre-transplant donor-specific antibodies (DSA), despite negative cytotoxicity and flow cytometry crossmatches (FCXMs), is unknown. We performed a retrospective cohort study of 60 living donor renal transplant recipients, all with pre-transplant cytotoxicity and T-cell and B-cell FCXMs that were negative. Twenty recipients had pre-transplant DSA detected by enzyme-linked immunosorbent assays (ELISA) and/or microbead methods. Forty contemporaneous DSA-negative controls were selected. In the DSA-positive group, after a median follow-up of 8.2 months (25-75% range, 5.4-22.8 months), patient survival was 100% and allograft survival was 95.0%. Acute humoral rejection (AHR) developed in four patients (20.0%). Three of the AHR episodes occurred within the first month post-transplant. Median serum creatinine at last follow-up was 1.3 mg/dL (25-75% range, 1.0-1.6 mg/dL), versus 1.1 mg/dL (25-75% range, 0.9-1.4 mg/dL) in the DSA-negative controls (p = 0.29). Only one of the 40 controls developed AHR (2.5%). Pre-transplant DSA was associated with a significantly increased incidence of AHR (p = 0.02 by log-rank test). In conclusion, despite negative pre-transplant cytotoxicity and FCXMs, renal transplant recipients with pre-transplant DSA detected by solid-phase methods may have an increased incidence of AHR and require close monitoring post-transplant.     

Posttransplant De Novo Donor‐Specific HLA Antibodies Identify Pediatric Kidney Recipients at Risk for Late Antibody‐Mediated Rejection

The emerging role of humoral immunity in the pathogenesis of chronic allograft damage has prompted research aimed at assessing the role of anti‐HLA antibody (Ab) monitoring as a tool to predict allograft outcome. Data on the natural history of allografts in children developing de novo Ab after transplantation are limited. Utilizing sera collected pretransplant, and serially posttransplant, we retrospectively evaluated 82 consecutive primary pediatric kidney recipients, without pretransplant donor‐specific antibodies (DSA), for de novo Ab occurrence, and compared results with clinical–pathologic data. At 4.3‐year follow up, 19 patients (23%) developed de novo DSA whereas 24 had de novo non‐DSA (NDSA, 29%). DSA appeared at a median time of 24 months after transplantation and were mostly directed to HLA‐DQ antigens. Among the 82 patients, eight developed late/chronic active C4d+ antibody‐mediated rejection (AMR), and four C4d‐negative AMR. Late AMR correlated with DSA (p < 0.01), whose development preceded AMR by 1‐year median time. Patients with DSA had a median serum creatinine of 1.44 mg/dL at follow up, significantly higher than NDSA and Ab‐negative patients (p < 0.005). In our pediatric cohort, DSA identify patients at risk of renal dysfunction, AMR and graft loss; treatment started at Ab emergence might prevent AMR occurrence and/or progression to graft failure.     

Control of antidonor antibody production with tacrolimus and mycophenolate mofetil in renal allograft recipients with chronic rejection

BACKGROUND: In renal transplantation, chronic rejection is a major cause of late allograft loss. Recent studies indicate that a subset of chronic rejection is associated with anti-HLA donor specific antibodies (DSA) and complement C4d deposition in peritubular capillaries (PTC). Since rescue therapy with tacrolimus and mycophenolate mofetil has been found to limit antidonor B-cell responses in recipients with acute humoral rejection, we sought to determine whether a similar immunosuppressive regimen might be effective in patients with 'chronic humoral rejection'. METHODS: Four renal allograft recipients with 'chronic humoral rejection' were prospectively identified. The diagnosis was based on: (1) progressive rise in serum creatinine over 12 months; (2) typical pathologic features by light microscopy (transplant arteriopathy and glomerulopathy); (3) widespread C4d deposits in PTC by immunofluorescence; (4) detection of 'de novo' DSA at the time of biopsy. Maintenance immunosuppression was CsA, prednisone and azathioprine (n=3) or prednisone and azathioprine (n=1). Rescue therapy with tacrolimus and mycophenolate mofetil was initiated in all patients, 12 hr after cyclosporine and azathioprine discontinuation. RESULTS: At diagnosis, the mean serum creatinine was 3.9 mg/dl (range: 3.3 to 5.4 mg/dl). DSA was an IgG directed against HLA class II (n=3) or class I (n=2), that is one patient had both anti-HLA class I and class II antibodies. Pretreatment antibody titers varied between 1:8 and 1:128. Rescue therapy was associated with a rapid and sustained decrease in antibody titers. In two patients, DSA became undetectable after 9 months and a repeat biopsy performed after 12 months revealed a decrease in C4d deposition in PTC. CONCLUSION: These results suggest that a decrease in DSA production can be induced in renal allograft recipients with 'chronic humoral rejection' by using an immunosuppressive regimen that combines tacrolimus and mycophenolate mofetil. Limitation of antidonor antibody synthesis may be important for the treatment or the prevention of chronic rejection in organ transplantation.     

The role of anti-HLA antibodies in heart transplantation

The major threat to long-term survival of heart allograft recipients is the development of graft atherosclerosis, which seems to be a manifestation of chronic rejection. To assess the role of anti-HLA antibodies in heart allograft rejection we studied 107 patients and compared the survival of recipients who formed anti-HLA antibodies with the survival of recipients who developed no antibodies. At 4 years the actuarial survival was 90% in the nonproducer group and 38% in antibody-producers (P = 0.038). We further explored the possibility that HLA antigens from the injured graft are released into the circulation and can be found in the serum either free or complexed with anti-HLA antibodies. This hypothesis was confirmed by the finding that the frequency of sera containing soluble HLA antigens from the graft or immune complexes of HLA alloantigens with anti-HLA antibodies was significantly higher in patients who rejected compared with patients with successful heart allografts (P less than 0.05). Following depletion of soluble HLA antigens, anti-HLA antibodies became detectable in 53% and 74% sera obtained during the first and second year posttransplantation, respectively, from patients undergoing chronic rejection. Long-term survivors showed a significantly lower (P less than 0.001) frequency of anti-HLA antibodies in sera depleted of HLA antigens. Lastly, studies of anti-anti-HLA-A2 and A3 antibodies in recipient sera suggest that quiescence is maintained by antiidiotypic antibodies.     

Identification of the antibodies involved in B-cell crossmatch positivity in renal transplantation

BACKGROUND: The significance of a positive B-cell crossmatch (BCM) in kidney transplantation has always been controversial in the evaluation of its implications on graft survival and specificity of the antibodies involved. METHODS: We have investigated the sera of 62 recipients of a kidney allograft transplanted across a positive BCM (T negative) for the presence of autoantibodies and anti-human leukocyte antigen (HLA) class I and II antibodies, using a combination of lymphocytotoxicity, enzyme-linked immunosorbent assay (ELISA), and flow cytometry tests. The controls were the 930 patients transplanted over the same period of time with a negative T and BCM. RESULTS: Autoantibodies were detected in 16%, and donor specific anti-HLA class II antibodies, mainly DQ, in 23% of the patients. None had antibodies against donor HLA class I. The target of the antibodies was not identified in 61%. Graft survival was comparable in the controls and in the +BCM patients, with nondonor-specific HLA reactivity. Patients with donor-specific anti-HLA class II antibodies had lower early graft survival and a higher incidence of vascular rejection. However, long-term allograft survival was similar to that of the other groups. CONCLUSION: These data suggest that in 77% of the patients, BCM positivity was not related with anti-HLA antibodies, and, in this case, graft survival was similar to that of the -BCM controls. In a minority of patients, anti-HLA class II antibodies were responsible for the +BCM, and their presence was associated with lower early, but not long-term, graft survival. Consequently, a +BCM should not systematically contraindicate kidney transplantation.     

动态分析HLA和MICA特异性抗体对移植肾功能的影响

目的 探讨肾移植前后人类白细胞抗原(HLA)和主要组织相容性一类相关链A基因(MICA)抗体特异性对移植后排斥反应和移植肾功能的影响. 方法采用免疫荧光液相芯片技术检测27例肾移植(尸供22例,亲属活体供肾5例)受者手术前后抗HLA抗体和MICA抗体的特异性和阳性值变化,并结合供受者的基因分型,区分供体特异性抗体和非供体特异性抗体.取同期的临床资料和SCr水平进行分析. 结果 27例移植患者中带肾存活26例,移植肾失功1例.移植后1、3、6、12个月时动态随访24例,失访2例.27例患者移植前预存抗体7例(25.9%),其中HLA抗体阳性2例、MICA抗体阳性3例,HLA和MICA抗体均阳性2例.肾移植前HLA和MICA抗体均阴性者中移植后3～6个月产生新生抗体3例.1例新生HLA-Ⅱ类特异性抗体者,移植半年后出现慢性排斥反应,经治疗术后1年SCr>200 btmol/L.3例肾移植前MICA抗体阳性者,术后MICA抗体的特异性均无改变,但抗体的阳性分值呈现2～8分的变化,1年后均升高到移植前(4～8分)水平.移植前预存低阳性率HLA-Ⅱ类特异性抗体者1例,移植后2周有发热等排斥反应,巨细胞病毒检测阳性,移植后1个月时SCr为171μmol/L,3个月升高到236μmol/L.24例分为抗体阴性组(14例)和抗体阳性组(10例).移植后1个月和1年时SCr水平2组间比较差异有统计学意义(P=0.03,0.05). 结论 移植后3～6个月是新生抗体变化的重要随访时间,可根据HLA和MICA抗体的特异性和阳性分值变化,尽早采取有效方法预防排斥反应和减少移植肾功能减退的发生和发展.     

动态监测供者特异性抗体与非供者特异性抗体判断移植肾预后的临床意义

目的 动态监测肾移植前后供者HLA特异性抗体(DSA)及非供者HLA特异性抗体(NDSA)的变化,观察其对移植肾预后的影响.方法 采用免疫荧光液相芯片(Luminex)技术检测8例肾移植患者术前HLA基因分型、术前和术后的特异性HLA抗体改变.结果 术前HLA抗体阴性者4例,术后1例并发肺部感染死亡,另3例半年内HLA抗体阴性,肾功能良好.2例移植前后检测HLA抗体阳性,术后半年抗体滴度明显逐渐增高,分离出DR11(DSA);DR12、DQ7、DQ8(NDSA).1例术前存在A11(DSA),A34(NDSA)抗体,术后1个月始NDSA增多,且其分值呈上升趋势.1例术前存在DR.15(DSA)抗体,术后1周发生急性排斥反应行移植肾切除.结论 肾移植前受者存在DSA会导致移植肾急性排斥,特别是存在HLA-Ⅱ类抗体.在随访期间HLA抗体滴度和类型持续升高者,应鉴定其DSA与NDSA类型,尽早采用有效的治疗方法 减少移植肾功能减退及排斥反应的发生和发展.     

Extremely High Association Between Appearance of HLA Antibodies and Failure of Kidney Grafts in a Five-Year Longitudinal Study

Longitudinal studies were conducted over a five-year period for HLA antibodies on 493 sera tested from 54 kidney transplant patients. HLA single antigen beads were employed to establish donor specificity of the antibodies. Only 3 of 22 patients without antibodies rejected a graft in contrast to 17 out of 32 patients with posttransplant antibodies (p = 0.003). Using a serum creatinine value of 4.0 mg/dL as the cut-off for a failed graft, 4 of 22 patients without antibodies failed compared to 21 of 32 with antibodies (p = 0.0006). Among patients with donor-specific antibodies (DSA) 13 of 15 failed (p = 0.000004). Even among patients with non-donor specific antibodies (NDSA), 8 of 17 failed (p = 0.05). Among patients who could be identified as making de novo antibodies (since they developed antibodies while not having antibodies for more than six months after transplantation), 6 of 11 failed (p = 0.03). Sequential testing for HLA antibodies shows that antibodies appear prior to a rise in serum creatinine and subsequent graft failure. The very strong association between the production of HLA antibodies after transplantation and graft failure indicates the importance of monitoring for posttransplant HLA antibodies.     

Significance of HLA-matching and anti-HLA antibodies in heart transplant patients receiving induction therapy?

ObjectivesThough Human Leukocyte Antigen (HLA) matching benefits are demonstrated in renal transplantation, evidence in heart transplantation is lacking, and its clinical feasibility is uncertain. Post-transplantation anti-HLA antibodies are being increasingly studied in organ transplantation, with diverging conclusions between transplantated organs.MethodsWe analyzed retrospectively the influence of HLA matching and anti-HLA antibodies on overall survival, acute rejection and chronic allograft vasculopathy in 309 patients receiving induction therapy and triple-drug immunosuppression.ResultsThe average number of HLA-A/B/DR mismatches between donor and recipient was 4.9 ± 1. The majority of mismatches was for Class I HLA-A/B with an average of 3.3, then for Class I HLA-DR with an average of 1.6. Overall, the HLA-A/-B/-DR mismatches had no influence on the cardiac allograft survival (p = 0.28). However, HLA-DR mismatches were negatively correlated to severe cellular and/or humoral allograft rejection (p = 0.04). Our analysis found anti-HLA antibodies in 27% of recipients, de novo anti-HLA antibodies in 16% of recipients, and donor-specific anti-HLA (DSA) antibodies in 8% of recipients. Furthermore, de novo DSA had no influence on the 5-year survival (78% with DSA vs. 92% without DSA; p = 0.49), which may be masked by the limited number of recipients in analysis By univariable analysis, anti-HLA antibodies (preexisting or de novo) unrelated or related to the donor had no influence on severe cellular and/or humoral rejection or on chronic allograft vasculopathy.ConclusionsHLA-DR mismatch was negatively correlated to severe cellular and/or humoral allograft rejection but had no influence on cardiac allograft survival. In this study, anti-HLA antibodies (preexisting or de novo) unrelated or related to the donor had no influence on cellular and/or humoral rejection or on chronic allograft vasculopathy. The results of this study add to the controversy on the impact of allo-antibodies in heart transplant recipients receiving induction therapy and contemporary immunosuppression.     

抗HLA和抗MICA抗体的表达对移植肾功能和急性排斥反应的预示作用

目的 探讨抗HLA与抗主要组织相容性复合物Ⅰ类链相关基因A(MICA)抗体的表达对移植肾功能和急性排斥反应的预示作用.方法 采用免疫磁珠流式液相芯片技术检测41例肾移植受者移植前后的抗HLA和抗MICA抗体,其中37例接受了1、3、6个月及1、2、3年的动态随访.分析抗HLA和抗MICA抗体的特异性,及其与血清肌酐和排斥反应的相关性.结果 移植前共有9例(22.0%,9/41)预存抗HLA或(和)抗MICA抗体,其巾抗HLA抗体阳性2例(4.9%,2/41),抗MICA抗体阳性6例(14.6%,6/41),抗HLA和抗MICA抗体均阳性1例(2.4%,1/41).另外有5例抗MICA抗体可疑阳性.除1例的抗MICA抗体为供者特异性抗体(DSA)外,其余均为非供者特异性抗体(NDSA).37例随访者中,6例新生抗HLA抗体(16.2%),3例新生抗MICA抗体(8.1%),新生抗HLA抗体者的抗体滴度在随访3年中呈现上升趋势.9例预存抗体的受者,有4例(44.4%,4/9)发生排斥反应;6例新生抗HLA抗体的受者中,有3例(50.0%)发生急性排斥反应,而3例新生抗MICA抗体的受者均无排斥反应发生,二者间的差异有统计学意义(P＜0.05).新生抗HLA抗体产生较早(术后3 d和7 d)的2例受者均检测到抗HLAⅡ类DSA,其移植肾均因排斥反应而切除.预存抗MICA抗体,且移植后发生排斥反应者在随访的每个时间点上的血清肌酐水平均高于预存抗MICA抗体但无排斥反应者(P＜0.05);移植前抗HLA和抗MICA抗体均阴性者,术后发生排斥反应者在随访的每个时间点上的血清肌酐水平均高于抗体阴性且无排斥反应者(P＜0.01);无论是新生抗HLA抗体还是抗MICA抗体,移植后1个月发生排斥反应者的血肌酐均明显高于抗体阴性且无排斥反应者(P＜0.01).结论 预存和新生抗HLA抗体是移植后发生急性排斥反应的重要因素,而供、受者HLA和MICA基因错配是产生新生抗体的重要原因.     

Effects of mycophenolate mofetil on donor-specific antibody formation in renal transplantation

BACKGROUND: Mycophenolate mofetil (MMF) is a routinely used immunosuppressive agent that selectively blocks T- and B-lymphocyte proliferation. The present study was designed to investigate the effects of this drug on human leukocyte(HLA) antibody production in general and donor-specific antibody (DSA) formation in particular in 154 recipients of renal allografts. PATIENTS AND METHODS: Renal allograft recipients were subdivided into three groups. Group 1 patients (n = 60) had received MMF since transplantation in combination with either cyclosporin A or tacrolimus and steroids. Group 2 patients (n = 29) had received an MMF-free immunosuppressive regimen initially followed by addition of MMF some time later. Group 3 patients (n = 65) had received no MMF. Cyclosporin A or tacrolimus in combination with azathioprine and/or steroids were used for immunosuppression. DSA were demonstrated by enzyme-linked immunosorbent assay (ELISA) for detection of panel-reactive antibodies of HLA class I and II specificity. RESULTS: The HLA antibodies were found in 16.7%, 27.6% and 30.8% of transplant recipients in groups 1, 2 and 3, respectively. DSA were found in 8.3%, 17.2% and 20.0%, and non-DSA in 10.0%, 20.7% and 24.6%, of patients in groups 1, 2 and 3, respectively. CONCLUSION: The MMF reduces anti-HLA class I and II antibody production and consequently DSA production in renal allograft recipients. Our data indicate this effect to be more pronounced in patients given MMF immediately after transplantation than in those in whom MMF is introduced some time later. The presence of DSA in the serum of renal allograft recipients is associated with poorer graft function (higher serum creatinine and more rejection episodes).     

Peritransplant Immunoadsorption for Positive Crossmatch Deceased Donor Kidney Transplantation

Various desensitization protocols were shown to enable successful living donor kidney transplantation across a positive complement‐dependent cytotoxicity crossmatch (CDCXM). Positive crossmatch transplantation, however, is less well established for deceased donor transplantation. We report a cohort of 68 deceased donor renal allograft recipients who, on the basis of broad sensitization (lymphocytotoxic panel reactivity ≥40%), were subjected to a protocol of peritransplant immunoadsorption (IA). Treatment consisted of a single session of immediate pretransplant IA (protein A) followed by posttransplant IA and antilymphocyte antibody therapy. Twenty‐one patients had a positive CDCXM, which could be rendered negative by pretransplant apheresis. Solid phase HLA antibody detection revealed preformed donor‐specific antibodies (DSA) in all 21 CDCXM‐positive and in 30 CDCXM‐negative recipients. At 5 years, overall graft survival, death‐censored graft survival and patient survival were 63%, 76% and 87%, respectively, without any differences between CDCXM‐positive, CDCXM‐negative/DSA‐positive and CDCXM‐negative/DSA‐negative recipients. Furthermore, groups did not differ regarding rates of antibody‐mediated rejection (24% vs. 30% vs. 24%, p = 0.84), cellular rejection (14% vs. 23% vs. 18%, p = 0.7) or allograft function (median 5‐year serum creatinine: 1.3 vs. 1.8 vs. 1.7 mg/dL, p = 0.62). Our results suggest that peritransplant IA is an effective strategy for rapid desensitization in deceased donor transplantation.     

Anti-HLA antibodies in kidney transplanted patients

Anti-human leukocyte antibodies (HLA) play a central role in graft survival, particularly in kidney transplantation. The presence of preformed donor specific anti-HLA antibodies is always excluded before transplantation by performing crossmatches using current and historic recipient serum samples. Several recent studies have observed a correlation between HLA antibodies and graft rejection. It has been suggested that these antibodies should be monitored routinely after kidney transplant to predict graft failure. Here in report the results of a study of on serum samples from 111 kidney transplant recipients that were monitored for anti-HLA antibodies using flow cytometry. Anti-HLA antibodies were only detected in four pre-immunized patients and showed the same HLA specificity that was present before the transplantation (in two cases against previous graft antigens). Furthermore, only two patients with functioning grafts developed anti-HLA antibodies, at 1 month and 1 year after the transplantation. However, they were not donor specific, but probably related to posttransplant transfusions. In our study, none of the patients who suffered an adverse event during the first year (including two with histologically documented acute rejection) developed anti-HLA antibodies. These results are probably related to the use of mycophenolate mofetil, which may reduce the incidence of HLA antibodies. We cannot exclude the possibility that antibodies produced by some patients may not be detectable because they are attached to the graft.     

Successful rescue and maintenance of long-term remission of anti-HLA antibody-mediated acute allograft rejection by rituximab-containing therapy: case report

Abstract:  A 38-yr-old man with chronic renal failure received a second kidney transplantation from a cadaveric donor. Complement-dependent cytotoxicity cross-match (CDC) was negative against T cells, but positive with the B-cell warm test. Human leukocyte antigen (HLA)-typing showed a one haplo-identical match. The blood type was compatible. He was treated with tacrolimus, mycophenolate mofetil (MMF), methylpredonisolone (MP), and basiliximab as immunosuppressive therapy. A clinical episode graft biopsy and Flow-PRA on post-operative day (POD) 19 showed anti-HLA antibody-mediated acute rejection (AHR). The patient was treated with plasmapheresis (PP). Renal biopsy performed on POD 65 because of re-rise of serum creatinine level showed worsening of renal injury. The patient was treated with rituximab (100 mg/body) with PP and MP pulse therapy, followed by tacrolimus and MMF. Graft function thereafter improved. A renal allograft biopsy specimen on POD 300 and Flow-PRA showed the remission of AHR within one-yr after transplantation.