Successful cadaveric renal transplantation of patients highly sensitized to HLA Class I antigens

The purpose of our investigation was to evaluate long-term graft survival and the role of histocompatibility in patients who were highly sensitized to human leukocyte antigen (HLA) Class I antigens and received a cadaveric renal transplant. Our multi-institutional study evaluated 7-yr graft outcomes and the histocompatibility requirements of 61 (6.1%) highly sensitized (anti-human globulin panel reactive antibody [AHG PRA], > or = 80%) cadaveric renal transplantation patients, transplanted between 1988 and 1997, among 999 consecutive cadaveric renal transplants. One- and 7-yr graft survival in the high PRA group (n = 61) was 76 and 59%, and was not significantly different from that in the low PRA group (n = 938), 86 and 59% (Wilcoxon = 0.11; log-rank = 0.45) (died with a functioning graft [DWFG] not censored). When those data were divided into primary and regrafts, 1- and 7-yr graft outcomes for high and low PRA groups were not significantly different [(primary, 1- and 7-yr survival: high PRA = 83 and 74%, n = 30, and low PRA = 87 and 61%, n = 825; log-rank = 0.37 for DWFG not censored) (regrafts, 1- and 7-yr survival: high PRA = 70 and 42%, n = 31, and low PRA = 80 and 43%, n = 113; log-rank = 0.36 for DWFG not censored)]. We did observe a subgroup of the high PRA patient group that had inferior graft outcomes. Graft outcome at 1 and 6 yr in the high PRA group for patients who had one to two DR mismatches (65 and 50%, n = 41) was significantly worse than for high PRA patients who had zero DR mismatches with their donors (100 and 78%, n = 20) (log-rank = 0.01 for DWFG not censored). Furthermore, the mean number of HLA-A and -B mismatches was significantly greater in the high PRA/DR-mismatched group (1.7 +/- 1.2, n = 41) compared with the high PRA/zero DR-mismatched group (0.5 +/- 1.1, n = 19) (p < 0.001). Overall, these data suggest that the patient who is highly sensitized to HLA Class I antigens has a long-term graft outcome that is equivalent to less sensitized patients, but that HLA-DR mismatching and a higher degree of Class I mismatching may be poor prognostic indicators in such patients.     

高致敏肾移植受者HLAI类抗体表位分析

目的探讨高致敏肾移植受者的HLAI类抗体的致敏表位。方法采用酶联免疫吸附法动态测定54例高致敏肾移植受者的HLAI类抗体特异性,并指定可能的抗体公共表位。结果90.7%(49/54)的高致敏受者具有可指定的抗体公共表位;最常见的公共表位是163E、142145TTKH、83R、7174AQTD、127K、163R、163L、41T、6266RNTRN和4145ASPRT;在动态监测过程中,抗体公共表位分析结果稳定,与抗体特异性鉴定比较,能更准确地反映抗体谱。结论高致敏受者的HLA抗体产生有明显的规律,对少数高频率、高免疫原性氨基酸残基的致敏是高致敏受者致敏的主要原因;对高致敏受者进行抗体表位分析能够准确地预测可接受的供者抗原错配。     

Abnormal B-cell regulation in highly sensitized patients with sustained serum levels of antibody to HLA class I antigens

BACKGROUND: There are anti-idiotypes in the sera of highly sensitized (HS) patients that stimulate B cells to produce antibody to HLA class I antigens. The purpose of this study is to determine if there is an abnormality in B cell responses to these anti-idiotypes. METHODS: Supernatants from normal and HS B cells exposed to either HLA-like anti-idiotypes or HS sera were tested for IgG and antibody to HLA class I antigens by ELISA and flow beads. RESULTS: When stimulated with HS sera, HS B cells produced antibody to HLA class I antigens (in vitro) (12/12) but normal B cells did not (0/10) (P<0.0001). When HS B cells were stimulated with isolated HLA-like anti-idiotypes, they produced more total IgG in the supernatant (603+/-105 ng/ml vs. 293+/-30 ng/ml; P<0.01) and more IgG1 (67+/-5.3 ng/ml vs. 32.3+/-5.4 ng/ml; P<0.001) and more IgG3 (33.3+/-9.2 vs. 2.03+/-0.2 ng/ml; P<0.0001) than normal B cells. The proliferative response to HLA-like anti-idiotypes was 1285+/-115 cpm from normal B cells and 1020+/-445 from HS B cells (p=NS). CONCLUSIONS: When exposed to HS sera, HS B cells produced antibody to HLA class I antigens and normal B cells did not. When exposed to isolated HLA-like anti-idiotypes, HS B cells produced more total IgG, primarily IgG1 and IgG3 with normal proliferation. This intrinsic abnormality in HS B cells permits antibody to HLA class I antigens to be produced and allows increased amounts of IgG1 and IgG3 to be secreted in the absence of an increase in proliferation.     

Determination of acceptable HLA mismatches in highly sensitized patients by soluble HLA class I ELISA inhibition

BACKGROUND: Acceptable HLA mismatches for highly sensitized patients are determined so as to increase their chances of receiving transplants. The disadvantage of the current procedures is that the antibody reactivity of the patients' sera is tested against HLA antigens expressed on cells or HLA antigens isolated from cell lysates. Therefore, two (homozygous for HLA-A and -B) to four (heterozygous for HLA-A and -B) different HLA class I antigens are present in the test. This might cause reactivity toward nonacceptable mismatches to mask the determination of acceptable mismatches. METHODS: Recently we observed that the detection of soluble HLA class I antigens is inhibited by HLA-specific antibodies. In the present study, inhibition of soluble HLA-specific ELISAs (anti-soluble HLA-A2, -B7, -B12) was evaluated as a tool used to determine acceptable mismatches. The results were compared with current determination of acceptable mismatches (which is by complement-dependent cytotoxicity and/or fluorescence-activated cell sorter analysis). RESULTS: In the case of acceptable mismatches determined by conventional methods, sera from the patients were not interfering in these ELISAs, whereas in the case of nonacceptable mismatches (thus specific antibodies), significant inhibition was observed in most instances. Among the nonacceptable mismatches, the test showed significant inhibition in 20 of 24 cases, whereas among acceptable mismatches, no inhibition was observed (in eight of eight), indicating the lack of specific antibodies. CONCLUSIONS: In highly sensitized patients, the introduction of soluble HLA-specific ELISAs is of additional and confirmatory value for the determination of acceptable mismatches. The major advantage of this approach is that antibody reactivity is tested against single antigens only.     

Hidden perils in a highly sensitized kidney transplant recipient

Highly sensitised patients are at increased risk for antibody mediated rejection (AMR) and reduced graft survival. Highly sensitive assays for detecting recipient preformed anti-HLA antibodies have been developed and identify high immunological risk donors. A 62yo male with end stage renal failure secondary to glomerulonephritis received a T-cell crossmatch negative, deceased donor, renal transplant mismatched at 3 of 6 HLA loci. A donor specific antibody (DSAb) to DR17 (MFI 2073) was present. Given his advancing age, multiple medical comorbidities and broad HLA sensitisation the transplant was accepted, however, shortly before transplantation two atypical results were made available. Firstly a B-cell crossmatch was performed and found to be negative in current serum but strongly positive in peak serum, secondly a further potential DSAb was predicted based on linkage disequilibrium with known donor HLA typing. The donor HLA typing would not be clarified until after the transplant. Despite the increased risk of AMR the transplant proceeded with pre-emptive plasma exchange. The patient developed severe AMR requiring extensive therapy. Incomplete prospective donor HLA typing can generate uncertainty in the interpretation of the virtual crossmatch performed for deceased donor transplants. This may result in clinically relevant sequelae. Advances in antibody detection techniques need to be matched by timely donor HLA typing for its full benefit to be realised.     

高致敏肾移植受者HLAⅠ类抗体表位分析

目的：探讨高致敏肾移植受者的HLAⅠ类抗体的致敏表位。方法：采用酶联免疫吸附法动态测定54例高致敏肾移植受者的HLAⅠ类抗体特异性，并指定可能的抗体公共表位。结果：90．7％(49／54)的高致敏受者具有可指定的抗体公共表位；最常见的公共表位是：163E、142-145TKH、83R、71—74AQTD、127K、163R、1631L、41T、62—66RNTRN和41—45ASPRT；在动态监测过程中，抗体公共表位分析结果稳定，与抗体特异性鉴定比较，能更准确地反映抗体谱。结论：高致敏受者的HLA抗体产生有明显的规律，对少数高频率、高免疫原性氨基酸残基的致敏是高致敏受者致敏的主要原因；对高致敏受者进行抗体表位分析能够准确地预测可接受的供者抗原错配。     

HLA class II specificities in vasculitis with antibodies to neutrophil cytoplasmic antigens.

HLA class II genes were examined in patients with small vessel vasculitis associated with anti-neutrophil cytoplasmic antibodies (ANCA) using restriction fragment length polymorphism and allele specific oligonucleotide typing. Fifty-nine patients were studied, 34 with Wegener's granulomatosis and 25 with microscopic polyarteritis, and their results were compared with those from 1103 British Caucasoid controls. The frequency of HLA-DQw7 was significantly increased in patients with vasculitis (patients 53%; controls 27.8%, chi 2 17.8, Pc less than 0.0025, relative risk 2.9), and all the DQw7 bearing haplotypes commonly found in Caucasoid populations contributed to the increase. By contrast, the frequency of HLA-DR3 bearing haplotypes was decreased in the patients (patients 6.8%; controls 21.6%, chi 2 6.7, P less than 0.01). HLA specificities were similar in the groups of patients presenting with Wegener's granulomatosis and microscopic polyarteritis and with different types of ANCA assessed by indirect immunofluorescence. However, patients with the DQw7, DR4 haplotype were significantly more likely to have transiently positive tests for ANCA than patients with other DQw7 bearing haplotypes, whereas patients with DR2 bearing haplotypes were more likely to have persistently positive ANCA. These results show that HLA class II genes are associated with small vessel vasculitis and may influence the duration of the associated autoimmune response.     

Rituximab in highly sensitized kidney transplant recipients

OBJECTIVES: Rituximab, an anti-CD20 monoclonal antibody therapy, depletes B cells and suppresses antibody production. This study sought to describe the efficacy and safety of rituximab among seven highly sensitized kidney transplant patients. METHODOLOGY: A highly sensitized patient was defined as panel-reactive antibody (PRA) >30%, more than three pregnancies, or history of positive tissue crossmatch. Demographics, immunological risk profile, and immunosuppression were collected on all highly sensitized patients transplanted from March to July 2007 and given rituximab. We noted graft function as well as clinical events posttransplantation. RESULTS: The seven patients included in the study showed a mean age of 39 years (range = 17-60) and a mean follow-up of 3 months (range = 1.5-5). Their average PRA was 62% with mean HLA mismatches of three. Five patients (71%) were retransplantations; one had a history of a positive crossmatch, and two had multiple pregnancies. Two had donor-specific antibody, but negative tissue crossmatches. All had living donors. Six patients received a single dose of rituximab (375 mg/m(2)) 1 day prior to transplantation and one received two doses after 19 sessions of plasmapheresis. All were given tacrolimus, mycophenolate, and steroids combined with induction therapy using 30 mg alemtuzumab in 33%; two doses of 20 mg basiliximab in 33%; and seven doses of 1 mg/kg/dose of daclizumab in 14%. Mean shown creatinine levels were 1.1 and 1.2 mg/dL at 1 and 6 months posttransplantation. Two recipients experienced acute humoral rejections within 1 month after transplantation. Both were given steroid pulsing, one of whom was steroid-resistant necessitating alemtuzumab therapy and plasmapheresis. Graft function of both improved with creatinine values of 1.3 mg/dL on discharge. No episodes of infection were noted. CONCLUSIONS: Rituximab can be safely administered and may be effective to improve outcomes among highly sensitized kidney transplant patients.     

Algorithm to manage highly sensitized kidney transplant recipients in Poland

Objective

Programs for immunized transplant recipients are essential to achieve graft survivals comparable to those of non-immunized recipients. The threshold in Poland is a PRA by the complement-dependent cytotoxicity (CDC) method greater than 50%, which includes approximately 3.8% of the patients. At the same time the United Network for Organ Sharing there recipients represent approximately 16% of the waiting list in the United Network for Organ Sharing (UNOS). The underestimation of the immunized group in Poland may be due to differences in laboratory techniques to assess alloantibodies.

Materials and methods

This study investigated 55 potential recipients with a PRA by CDC > 50%. We used the following algorithm to assess their immunization: Luminex screening test for an HLA antibody; specificity assessed with Luminex Single Antigen, vPRA (evaluation of immunization of the patient); and analysis of acceptable HLA incompatibilities (HLAMatchmaker).

Results

All recipients were positive class I anti-HLA antibodies and 94.5% were positive for class II. For the groups of subjects with PRA-CDC from 50% to 79% versus those greater than 80%, the average values of PRA-CDC were 62.2% and 89.5%, respectively. The virtual PRA results for these groups were 95.7% and 97.2%, respectively. In addition, anti-HLA-Cw, anti-DQ and anti-DP antibodies were detected in 77%, 84%, and 51% of recipients, respectively. Immunized recipients reported to the next transplant were characterized by the antibodies against mismatch only in 68%. For all potential recipients, additional acceptable non-compliance was determined with HLAMatchmaker: 152 specificity for locus A and 252 for locus B.

Conclusions

Evaluation of immunization status of recipient candidates should be routinely performed using tests to assess class and specificity as well as level of alloantibodies to enable determination of a safe potential donor. As a routine test, PRA-CDC underestimates the number of highly immunized patients. Exclusion from the list of patients with repeated non-compliance is a simplification, which reduces their chance for transplantation.     

肾移植受者血清可溶性HLA-I类抗原的动态监测

目的　了解血清可溶性ＨＬＡＩ类抗原（ｓＨＬＡＩ） 与肾移植受者发生急性排斥反应及感染的关系。　方法　应用酶联免疫法动态监测３６ 例肾移植受者ｓＨＬＡＩ水平。　结果　尿毒症组ｓＨＬＡＩ水平为（２－９４±０－３４）μｇ／Ｌ,显著高于正常对照组（０－７６±０－３３）μｇ／Ｌ（Ｐ＜ ０－０５） 。移植后功能稳定组ｓＨＬＡ降至（０－６３±０－３１ ）μｇ／Ｌ,显著低于尿毒症组（ Ｐ＜０－０５）。ｓＨＬＡＩ在发生排斥反应前３ 天及感染后５～７ 天显著升高。　结论　ｓＨＬＡＩ可作为监测肾移植受者急性排斥反应和感染的参数。     

肾移植受者血清可溶性HLA—Ⅰ类抗原的动态监测

目的 了解血清可溶性ＨＬＡ－Ⅰ类抗原（ｓＨＬＡ－Ⅰ）与肾移植受发生急性排斥反应及感染的关系。方法 应用酶联免疫法动态监测３６例肾移植受ｓＨＬＡ－Ⅰ水平。结果尿毒症组ｓＨＬＡ－Ⅰ水平为（２．９４±０．３４）μｇ／Ｌ,显高于正常对照组（０．７６±０．３３）μｇ／Ｌ（Ｐ〈０．０５）。移植后功能稳定组ｓＨＬＡ降至（０．６３±０．３１）μｇ／Ｌ,显低于尿毒症组（Ｐ〈０．０５）。ｓＨＬＡ－Ⅰ在发生排斥     

Role of class I and class II HLA antigens in cadaveric renal transplantation

HLA matching at MT and DQ appears to be an important predictor of allograft survival. Allografts with no MM at MT and DQ have a good outcome while a known MM at MT and DQ appears to be associated with poor allograft outcome. Thus, our priority should be to avoid an MM for these broad-reacting specificities and then to minimize incompatibilities at DR and HLA-B. Furthermore, our data indicate that allografts with MM at DQ and two MMs at HLA-B appear to be at a higher risk. Perhaps these latter transplants should not be performed with conventional immunosuppressive therapy.     

Association of class II antigens of HLA with primary glomerulopathies

HLA antigens of Japanese patients with primary glomerulopathies were determined, and the frequency of each HLA antigen was compared with that of Japanese normal controls. IgA nephropathy with HLA-DR4, idiopathic membraneous glomerulopathy with DR2, lipoid nephrosis with DRw53 and poststreptococcal glomerulonephritis with DR1 were definitely or probably associated. It was suggested that primary glomerulopathies might all be associated with HLA class II and not class I antigens. Japanese patients with HLA-Bw48 and -DRw8 were less susceptible to primary glomerulopathies.     

Kidney graft failure and presensitization against HLA class I and class II antigens

BACKGROUND: It is well known that kidney transplant recipients with preformed lymphocytotoxic antibodies against HLA antigens have an increased graft rejection rate. However, the individual contribution of anti-HLA class I and class II antibodies to this phenomenon is poorly understood. We investigated the clinical relevance of preformed anti-HLA class I and class II antibodies on graft outcome in more than 4000 kidney recipients. METHODS: Pretransplant sera of 4136 cadaver kidney recipients from 28 transplant centers were tested in ELISA for IgG-anti-HLA class I and IgG-anti-HLA class II antibodies. The influence of antibody reactivity on graft survival was analyzed. RESULTS: Four hundred eighty of the anti-HLA class I antibody-positive recipients had a graft survival rate at 2 years of 77+/-2%, compared with an 84+/-1% rate in 3656 anti-HLA class I antibody-negative recipients (P<0.0001), and 770 anti-HLA class II-positive recipients had a graft survival rate of 79+/-2%, compared with an 84+/-1% rate in 3366 anti-HLA class II-negative patients (P<0.0001). Importantly, good 2-year graft survival rates of 85+/-3% and 84+/-2%, respectively, were observed in 206 anti-HLA class I-positive/class II-negative and 496 anti-HLA, class I-negative/class II-positive recipients. In contrast, the 274 recipients positive for both types of antibodies showed a poor graft survival rate of 71+/-3% (P<0.0001). Among 853 patients who received a well-matched kidney (0 or 1 HLA-A+B+DR mismatch), sensitization against either class I or class II, or both, had no deleterious effect. However, in 113 class I and class II antibody-positive patients who received a kidney with > or =3 HLA-A+B+DR mismatches, the 2-year graft survival rate was only 60+/-5%. CONCLUSION: Presensitization of first kidney transplant recipients against either HLA class I or class II is of no clinical consequence, whereas sensitization against both HLA class I and class II results in increased rejection of HLA mismatched grafts.     

The impact of belatacept on third‐party HLA alloantibodies in highly sensitized kidney transplant recipients

Recent evidence suggests that belatacept reduces the durability of preexisting antibodies to class I and class II human leukocyte antigens (HLAs). In this case series of 163 highly sensitized kidney transplant candidates whose calculated panel‐reactive antibody (cPRA) activity was ≥98% to 100%, the impact of belatacept on preexisting HLA antibodies was assessed. Of the 163 candidates, 72 underwent transplantation between December 4, 2014 and April 15, 2017; 60 of these transplanted patients remained on belatacept consecutively for at least 6 months. We observed a decrease in the breadth and/or strength of HLA class I antibodies as assessed by FlowPRA in belatacept‐treated patients compared to controls who did not receive belatacept. Specifically, significant HLA antibody reduction was evident for class I (P < .0009). Posttransplant belatacept‐treated patients also had a clinically significant reduction in their cPRA compared to controls (P < .01). Collectively, these findings suggest belatacept can reduce HLA class I antibodies in a significant proportion of highly sensitized recipients and could be an option to improve pretransplant compatibility with organ donors.     

HLA class I and II antigens in South African Indians with NIDDM

The relationship between the HLA system and non-insulin-dependent diabetes mellitus (NIDDM) in South African Indians, a migrant Indian group, was evaluated by testing HLA-A, -B, and -C antigens in 184 patients and 1444 control subjects and HLA-DR antigens in 104 patients and 330 control subjects. There was a significant increase in the frequency of HLA-Bw61 in patients compared with control subjects (27.7 vs. 18%, P = .00155), although the degree of association was not very strong (relative risk 1.7). A similar association has been noted in Fiji Indians, another migrant Indian group. However, no relationship could be established at the DR locus. It is suggested that the relatively high frequency of the Bw61 allele in South African Indians could, in the presence of some environmental factor like obesity, confer increased susceptibility to NIDDM.     

Successful third kidney transplantation with intensive immunosuppression in a highly sensitized recipient

HLA sensitization associated with previous kidney transplantation is a major drawback to retransplantation. Recently we successfully performed a third graft using intensive immunosuppression for a highly sensitized recipient. The patient was a 31-year-old man who had previously undergone a living donor graft from his father at our institute in 1999. His kidney graft function had deteriorated due to chronic allograft nephropathy, returning to hemodialysis therapy in 2005. He received a second graft from a deceased donor in another country on August 14, 2006. It rejected on postoperative day 3 possibly due to acute accelerated rejection. He was offered a third kidney from his brother. Panel-reactive antibody (PRA) tested before the third procedure revealed positive class I (88%) and class II (96%) PRAs. Mycophenolate mofetil (MMF) was started 3 weeks before the third transplantation, and preoperative plasmapheresis performed thrice. He underwent the living donor graft on March 9, 2007. Immunosuppression consisted of tacrolimus, MMF, methylprednisolone, and basiliximab. Immediately afterward there was a sudden decrease in allograft blood flow and urine output, implying hyperacute rejection. Following treatment with plasmapheresis and a single dose of rituximab (200 mg), the kidney allograft function recovered, although the PRA at 3 weeks was still positive. Six months posttransplantation, he is well with a creatinine of 0.9 mg/dL. Our protocol may reduce the risk for graft loss in a highly sensitized transplant recipient.