Paul I. Terasaki, PhD, 1929-2016.

Paul Terasaki was a pioneer of transplantation and had a global following. His career, which spanned >50 years, included accomplishments and discoveries that revolutionized the field of transplantation and that advanced the care of transplant patients. Paul is survived by his wife Hisako, his brother, four children and six grandchildren as well as legions of close friends and colleagues around the world who will continue to build on his successes.

Kidney paired donation in the presence of donor-specific antibodies.

Incompatible donor/recipient pairs with broadly sensitized recipients have difficulty finding a crossmatch-compatible match, despite a large kidney paired donation pool. One approach to this problem is to combine kidney paired donation with lower-risk crossmatch-incompatible transplantation with intravenous immunoglobulin. Whether this strategy is non-inferior compared with transplantation of sensitized patients without donor-specific antibody (DSA) is unknown. Here we used a protocol including a virtual crossmatch to identify acceptable crossmatch-incompatible donors and the administration of intravenous immunoglobulin to transplant 12 HLA-sensitized patients (median calculated panel reactive antibody 98%) with allografts from our kidney paired donation program. This group constituted the DSA(+) kidney paired donation group. We compared rates of rejection and survival between the DSA(+) kidney paired donation group with a similar group of 10 highly sensitized patients (median calculated panel reactive antibody 85%) that underwent DSA(-) kidney paired donation transplantation without intravenous immunoglobulin. At median follow-up of 22 months, the DSA(+) kidney paired donation group had patient and graft survival of 100%. Three patients in the DSA(+) kidney paired donation group experienced antibody-mediated rejection. Patient and graft survival in the DSA(-) kidney paired donation recipients was 100% at median follow-up of 18 months. No rejection occurred in the DSA(-) kidney paired donation group. Thus, our study provides a clinical framework through which kidney paired donation can be performed with acceptable outcomes across a crossmatch-incompatible transplant.

Calculated PRA: initial results show benefits for sensitized patients and a reduction in positive crossmatches.

The calculated panel reactive antibody (CPRA), which is based upon unacceptable HLA antigens listed on the waitlist form for renal transplant candidates, replaced PRA as the measure of sensitization among US renal transplant candidates on October 1, 2009. An analysis of the impact of this change 6 months after its implementation shows an 83% reduction in the number of kidney offers declined nationwide because of a positive crossmatch. The increasing acceptance and utilization of unacceptable HLA antigens to avoid offers of predictably crossmatch-positive donor kidneys has increased the efficiency of kidney allocation, resulting in a significant increase in the percentage of transplants to broadly sensitized (80+% PRA/CPRA) patients from 7.3% during the period 07/01/2001-6/30/2002 to 15.8% of transplants between 10/1/09-3/31/10. The transplant rates per 1000 active patient-years on the waitlist also increased significantly for broadly sensitized patients after October 1, 2009. These preliminary results suggest that 'virtual' positive crossmatch prediction based on contemporary tools for identifying antibodies directed against HLA antigens is effective, increases allocation efficiency and improves access to transplants for sensitized patients awaiting kidney transplantation.

Inflammation in areas of tubular atrophy in kidney allograft biopsies: a potent predictor of allograft failure.

The Banff scoring schema provides a common ground to analyze kidney transplant biopsies. Interstitial inflammation (i) and tubulitis (t) in areas of viable tissue are features in scoring acute rejection, but are excluded in areas of tubular atrophy (TA). We studied inflammation and tubulitis in a cohort of kidney transplant recipients undergoing allograft biopsy for new-onset late graft dysfunction (N = 337). We found inflammation ('iatr') and tubulitis ('tatr') in regions of fibrosis and atrophy to be strongly correlated with each other (p < 0.0001). Moreover, iatr was strongly associated with death-censored graft failure when compared to recipients whose biopsies had no inflammation, even after adjusting for the presence of interstitial fibrosis (Hazard Ratio = 2.31, [1.10-4.83]; p = 0.0262) or TA (hazard ratio = 2.42, [1.16-5.08]; p = 0.191), serum creatinine at the time of biopsy, time to biopsy and i score. Further, these results did not qualitatively change after additional adjustments for C4d staining or donor specific antibody. Stepwise regression identified the most significant markers of graft failure which include iatr score. We propose that a more global assessment of inflammation in kidney allograft biopsies to include inflammation in atrophic areas may provide better prognostic information. Phenotypic characterization of these inflammatory cells and appropriate treatment may ameliorate late allograft failure.

Histopathologic clusters differentiate subgroups within the nonspecific diagnoses of CAN or CR: preliminary data from the DeKAF study.

The nonspecific diagnoses 'chronic rejection''CAN', or 'IF/TA' suggest neither identifiable pathophysiologic mechanisms nor possible treatments. As a first step to developing a more useful taxonomy for causes of new-onset late kidney allograft dysfunction, we used cluster analysis of individual Banff score components to define subgroups. In this multicenter study, eligibility included being transplanted prior to October 1, 2005, having a 'baseline' serum creatinine < or =2.0 mg/dL before January 1, 2006, and subsequently developing deterioration of graft function leading to a biopsy. Mean time from transplant to biopsy was 7.5 +/- 6.1 years. Of the 265 biopsies (all with blinded central pathology interpretation), 240 grouped into six large (n > 13) clusters. There were no major differences between clusters in recipient demographics. The actuarial postbiopsy graft survival varied by cluster (p = 0.002). CAN and CNI toxicity were common diagnoses in each cluster (and did not differentiate clusters). Similarly, C4d and presence of donor specific antibody were frequently observed across clusters. We conclude that for recipients with new-onset late graft dysfunction, cluster analysis of Banff scores distinguishes meaningful subgroups with differing outcomes.

Pathological and clinical characterization of the 'troubled transplant': data from the DeKAF study.

We are studying two cohorts of kidney transplant recipients, with the goal of defining specific clinicopathologic entities that cause late graft dysfunction: (1) prevalent patients with new onset late graft dysfunction (cross-sectional cohort); and (2) newly transplanted patients (prospective cohort). For the cross-sectional cohort (n = 440), mean time from transplant to biopsy was 7.5 +/- 6.1 years. Local pathology diagnoses included CAN (48%), CNI toxicity (30%), and perhaps surprisingly, acute rejection (cellular- or Ab-mediated) (23%). Actuarial rate of death-censored graft loss at 1 year postbiopsy was 17.7%; at 2 years, 29.8%. There was no difference in postbiopsy graft survival for recipients with versus without CAN (p = 0.9). Prospective cohort patients (n = 2427) developing graft dysfunction >3 months posttransplant undergo 'index' biopsy. The rate of index biopsy was 8.8% between 3 and 12 months, and 18.2% by 2 years. Mean time from transplant to index biopsy was 1.0 +/- 0.6 years. Local pathology diagnoses included CAN (27%), and acute rejection (39%). Intervention to halt late graft deterioration cannot be developed in the absence of meaningful diagnostic entities. We found CAN in late posttransplant biopsies to be of no prognostic value. The DeKAF study will provide broadly applicable diagnostic information to serve as the basis for future trials.

Calculated PRA (CPRA): the new measure of sensitization for transplant candidates.

The ways we measure whether a patient is sensitized to HLA antigens and to what extent sensitization affects access to transplantation have changed remarkably during the past decade. What we mean by sensitized and broadly sensitized today is heavily dependent upon the sensitivity of the test that is used to measure antibodies. Because we provide additional allocation points for broadly sensitized patients in the United States kidney allocation system in an effort to compensate for their biological disadvantage, some consistency and accountability are required. The calculated panel-reactive antibody, which provides an estimate of the percentage of deceased organ donors that will be crossmatch incompatible for a candidate provides both consistency and accountability.

Should pediatric patients wait for HLA-DR-matched renal transplants?

Graft survival rates from deceased donors aged 35 years or less among all primary pediatric kidney transplant recipients in the United States between 1996 and 2004 were retrospectively examined to determine the effect of HLA-DR mismatches on graft survival. Zero HLA-DR-mismatched kidneys had statistically comparable 5-year graft survival (71%), to 1-DR-mismatched kidneys (69%) and 2-DR-mismatched kidneys (71%). When compared to donors less than 35 years of age, the relative rate of allograft failure was 1.32 (p = 0.0326) for donor age greater than or equal to age 35. There was no statistical increase in the odds of developing a panel-reactive antibody (PRA) greater than 30% at the time of second waitlisting, based upon the degree of HLA-A, -B or -DR mismatch of the first transplant, nor was there a 'dose effect' when more HLA antigens were mismatched between the donor and recipient. Therefore, pediatric transplant programs should utilize the recently implemented Organ Procurement and Transplantation Network's (OPTN)allocation policy, which prioritizes pediatric recipients to receive kidneys from deceased donors less than 35 years of age, and should not turn down such kidney offers to wait for a better HLA-DR-matched kidney.

Prospective registry-based observational cohort study of the long-term risk of malignancies in renal transplant patients treated with mycophenolate mofetil.

This large prospectively conducted observational cohort study examined the risk of lymphoma and other malignancies with mycophenolate mofetil (MMF) in de novo renal transplant recipients. A total of 6751 patients receiving MMF, and an equal number of matched controls receiving non-MMF-based immunosuppression, were identified from two large registries (Organ Procurement and Transplantation Network/United Network for Organ Sharing (OPTN/UNOS) and Collaborative Transplant Study (CTS)) and followed for 3 years. The primary endpoint was development of lymphoma. Secondary endpoints included development of any malignancy. There was no evidence of any increased risk of developing lymphoma or malignancy with MMF. The risk of developing lymphoma with MMF compared with the non-MMF cohort was not higher in either the CTS registry (relative risk (95% confidence interval); 0.4 (0.17-0.94)) or the OPTN/UNOS registry (1.04 (0.61-1.78)). In the MMF group, there was a trend toward a lower risk of malignancy in both registries (OPTN/UNOS 0.86 (0.69-1.07); CTS 0.79 (0.61-1.02)) and a significant increase in time to malignancy in the CTS dataset (p < 0.026). This study has demonstrated that MMF is not associated with an increased risk of lymphoma or other malignancies post-renal transplant, and may even be associated with a lower risk in some populations.

Determinants of long-term survival of pediatric kidney grafts reported to the United Network for Organ Sharing kidney transplant registry.

Pediatric 1-yr kidney graft survival rates have steadily improved in the US so that, by 1998, over 90% of hospital-discharged young recipients had survived the first year post-transplantation (Tx). However, 25% of the early surviving kidney grafts failed at 5 yr, yielding a projected half-life of 10 yr. Given a median age at transplant of 13 yr (range 0-20 yr), 50% of all current pediatric kidney recipients will need a second graft before the age of 25 years. We examined 8,422 pediatric renal transplants reported to the United Network for Organ Sharing (UNOS) Kidney Transplant Registry and, by using a log-linear multifactorial analysis, determined the relative influence of 26 major transplant factors on long-term graft survival. Results are reported as percentages of assignable variation (totaling 100% for all 26 factors combined) in pediatric outcomes beyond 1 yr and as adjusted graft survival rates. Transplant center, recipient race and age, transplant year, and panel-reactive antibody (PRA) had assignable variation percentages of 25, 24, 16, 12, and 4, respectively. When combined, they accounted for 81% of changes in long-term survival. Besides center effects, Blacks, teenagers, and transplants performed before 1994 exhibited significantly (p <0.0001) lower adjusted 5-yr graft survival rates as did the few sensitized (PRA>40%) pediatric patients (p = 0.02). Patients transplanted with a living donor kidney demonstrated a 5% point advantage at 5 yr post-Tx over cadaver donor kidneys (p = 0.001). Although the survival rate of pediatric kidney transplants has improved steadily, the long-term outcomes for teenagers and for Black recipients lag significantly behind those of younger patients and non-Blacks.

The UNOS renal transplant registry.

The shortage of cadaver kidneys relative to increasing demand for transplantation has lead to a remarkable rise in transplantation from living donors. Based upon data reported to UNOS, the number of living donor kidneys transplanted in 2000 (5,106) nearly equaled the number of cadaver kidneys from preferred donors aged 6-50. HLA-mismatched siblings, offspring, spouses and other genetically unrelated donors accounted for nearly 80% of increased living donor transplantation during 1994-2000. Despite the increased use of poorly HLA-matched living donor kidneys, the actuarial 10-year graft survival rates for transplants between 1988-2000 were clustered between 53-57% for HLA-mismatched living donor grafts, except for offspring-to-parent transplants (49%) when the recipients were generally older. The 10-year survival rate for 96,053 cadaver grafts was 38% during the same period. The 5-year graft survival rates for more recent (1996-2000) cadaver donor transplants were 66%, 62% and 56% for recipients of first, second and multiple grafts, respectively (p < 0.001). The comparable results among recipients of living donor kidneys were 67%, 66% and 59% (p = ns). The 5-year graft survival rates for HLA-matched first grafts were 7% higher than those for HLA-mismatched transplants when the kidney was from a living or cadaver donor. HLA-identical sibling transplants provided the best long-term graft survival (85% at 5 years and a 32 year half-life). Even with improved crossmatch tests and stronger immunosuppression, sensitization was associated with 8% lower graft survival at 5 years and with a higher rate of late graft loss among first cadaver kidney recipients. Sensitization also was associated with an increase in delayed graft function from 22% of unsensitized first transplant recipients to as much as 36% among multiply retransplanted patients. Recipient race was a key factor in long-term graft survival of both living and cadaver donor kidneys. The rate of late graft loss was double among blacks compared with recipients with other racial origins whether the kidney was from a living or cadaver donor. Black recipients accounted for 29% of first cadaver transplants during 1996-2000, but only 14% of living donor grafts. Thus an important component of long-term differences in graft survival comparing living and cadaver donor transplants is the disparate racial demographics. Both the recipient and donor populations are aging. The proportion of cadaver kidney recipients over age 50 increased from 26% to 45% and the proportion of living donor kidney recipients over age 50 rose from 10% to 35% between 1988 and 2000. The aging population affects the transplant outcome as 65% of graft losses among young recipients (ages 10-15) were attributed to acute or chronic rejection compared with only 25% of grafts lost among patients over age 60. More than half of graft losses among older recipients were due to death with a functioning graft. Kidneys from donors over age 60 comprised 9% of first cadaver transplants and yielded a 50% 5-year graft survival rate compared with 70% when the donor was aged 19-45. Kidneys from donors over age 60 accounted for only 3% of first living donor transplants and their 84% 5-year graft survival rate was comparable to that for younger donor kidneys. Despite declining immunological graft losses with advancing recipient age, the effect of HLA matching was similar among recipients of first cadaver transplants aged 50 or under and those over age 50. Completely HLA-mismatched grafts had a 10% lower 5-year graft survival rate than HLA-matched grafts when the recipient was over 50 compared with a 14% lower survival rate in younger recipients. The graft half-lives were shorter by 5-7 years for HLA-mismatched kidneys transplanted to older or younger recipients, respectively.

Crossmatch tests--an analysis of UNOS data from 1991-2000.

Based on more than 20,000 cadaver donor transplants reported to UNOS between 1991-2000 with crossmatch results, the following observations were made: 1. One-hundred sixty-nine transplants performed despite a positive T-cell NIH crossmatch (usually with an historical serum sample) were reported to UNOS and had 5%, 6%, 7%, and 11% lower graft survival at one, 6, 12, and 24 months after transplantation compared with negative crossmatch transplants, respectively. 2. Transplants with a positive T-cell FCXM (n = 714) yielded 4%, 7%, and 9% lower graft survival at one, 6, and 12 months after transplantation compared with negative crossmatch transplants, respectively. 3. Transplants with a positive B-cell crossmatch using NIH, Wash, AHG or flow cytometry XM yielded statistically significantly lower (4-6%) graft survival rates compared with B-cell negative crossmatch transplants. 4. The differences in graft survival rates comparing recipients with a positive versus a negative T-cell crossmatch test (NIH, AHG, and FCXM) were significant in univariate analyses; however, only the NIH and FCXM showed a significant effect on graft survival after adjustment of other factors in a multivariate analysis. 5. Regrafted patients with a positive T- and B-cell FCXM experienced a higher incidence of primary nonfunction (12%) compared with those who had a negative T- and B-cell FCXM (1%; P < 0.001). Flow cytometric or ELISA screening of patient sera in addition to conventional cytotoxic crossmatch tests can provide additional information to aid in the final decision of renal transplantation.

Flow cytometric detection of HLA-specific antibodies as a predictor of heart allograft rejection.

BACKGROUND: Historically, panel reactive antibody (PRA) analysis to detect HLA antibodies has been performed using cell-based complement-dependent cytotoxicity (CDC) techniques. Recently, a flow cytometric procedure (FlowPRA) was introduced as an alternative approach to detect HLA antibodies. The flow methodology, using a solid phase matrix to which soluble HLA class I or class II antigens are attached is significantly more sensitive than CDC assays. However, the clinical relevance of antibodies detected exclusively by FlowPRAhas not been established. In this study of cardiac allograft recipients, FlowPRA was performed on pretransplant sera with no detectable PRA activity as assessed by CDC assays. FlowPRA antibody activity was then correlated with clinical outcome. METHODS: PRA analysis by anti-human globulin enhanced (AHG) CDC and FlowPRA was performed on sera corresponding to final cross-match specimens from 219 cardiac allograft recipients. In addition, sera collected 3-6 months posttransplant from 91 patients were evaluated. The presence or absence of antibodies was correlated with episodes of rejection and patient survival. A rejection episode was considered to have occurred based on treatment with antirejection medication and/or histology. RESULTS: By CDC, 12 patients (5.5%) had pretransplant PRA >10%. In contrast, 72 patients (32.9%) had pretransplant anti-HLA antibodies detectable by FlowPRA (34 patients with only class I antibodies; 7 patients with only class II antibodies; 31 patients with both class I and class II antibodies). A highly significant association (P<0.001) was observed between pretransplant HLA antibodies detected by FlowPRA and episodes of rejection that occurred during the first posttransplant year. Fifteen patients died within the first year posttransplant. Of nine retrospective flow cytometric cross-matches that were performed, two were in recipients who had no pretransplant antibodies detectable by FlowPRA. Both of these cross-matches were negative. In contrast, five of seven cross-matches were positive among recipients who had FlowPRA detectable pretransplant antibodies. Posttransplant serum specimens from 91 patients were also assessed for antibodies by FlowPRA. Among this group, 58 patients had FlowPRA antibodies and there was a trend (although not statistically significant) for a biopsy documented episode of rejection to have occurred among patients with these antibodies. CONCLUSIONS: Collectively, our data suggest that pre- and posttransplant HLA antibodies detectable by FlowPRA and not AHG-CDC identify cardiac allograft recipients at risk for rejection. Furthermore, a positive donor reactive flow cytometric cross-match is significantly associated with graft loss. Thus, we believe that detection and identification of HLA-specific antibodies can be used to stratify patients into high and low risk categories. An important observation of this study is that in the majority of donor:recipient pairs, pretransplant HLA antibodies were not directed against donor antigens. We speculate that these non-donor-directed antibodies are surrogate markers that correspond to previous T cell activation. Thus, the rejection episodes that occur in these patients are in response to donor-derived MHC peptides that share cryptic determinants with the HLA antigens that initially sensitized the patient.

Twelve years' experience with national sharing of HLA-matched cadaveric kidneys for transplantation.

BACKGROUND: In October 1987, the United Network for Organ Sharing (UNOS) established a national kidney-sharing program to increase the number of HLA-matched transplantations. Since then, over 7500 cadaveric kidneys have been shipped to centers in 48 states for transplantation to HLA-matched patients. We evaluated the efficacy of the program during its first 12 years of operation. METHODS: We compared the rates of rejection and actuarial graft survival for 7614 HLA-matched and 81,364 HLA-mismatched cadaveric kidney transplantations reported to the UNOS Scientific Registry between October 1987 and September 1999. To assess the effects of the extended period of ischemia associated with shipping HLA-matched kidneys, we identified 3562 pairs of cadaveric kidneys in which one kidney went to an HLA-matched recipient and the other went to an HLA-mismatched recipient. RESULTS: The estimated 10-year rate of graft survival was 52 percent for HLA-matched transplants, as compared with 37 percent for HLA-mismatched transplants. The estimated half-lives of the transplants were 12.5 years and 8.6 years, respectively, and the mean duration of cold ischemia was 23 hours and 22 hours, respectively. After adjustment for the effects of demographic characteristics, at 10 years the overall rates of graft survival and the rates of functional-graft survival (with data censored on patients who died with a functioning graft) were 10 percent and 11 percent higher, respectively, for HLA-matched transplants than for HLA-mismatched transplants. Among 3562 pairs of kidneys, HLA-matched transplants had higher rates of survival, a lower incidence of episodes of rejection, and a lower risk of loss as a result of rejection. CONCLUSIONS: A superior graft outcome with little increase in the duration of cold ischemia justifies national sharing of HLA-matched kidney transplants.