Effect of crossmatching on outcome in organ transplantation

Psychosocial Assessment of Living Organ Donors: Clinical and Ethical Considerations

This article outlines psychosocial and ethical issues to be considered when evaluating potential living organ donors. Six types of living donors are described: genetically related, emotionally related, “Good Samaritan” (both directed and nondirected), vendors, and organ exchangers. The primary domains to be assessed in the psychosocial evaluation are informed consent, motivation for donating and the decision-making process, adequacy of support (financial and social), behavioral and psychological health, and the donor-recipient relationship. Obstacles to the evaluation process include impression management, overt deception, minimization of behavioral risk factors, and cultural and language differences between the donor and the evaluator. Ethical concerns, such as the right to donate, donor autonomy, freedom from coercion, nonmaleficence and beneficence in donor selection, conflicts of interest, “reasonable” risks to donors, and recipient decision making are also explored. To fully evaluate living organ donation, studying psychosocial as well as medical outcomes is crucial.

Significance of true-positive and false-positive pretransplantation lymphocytotoxic crossmatch in primary liver allograft outcomes

BACKGROUND

At the time of transplantation, a recipient's serum is tested against the prospective donor's lymphocytes to identify specific reactivity and to look for a donor-specific crossmatch (CXM). Here, we investigated the relationship between the pretransplantation lymphocytotoxic CXM results and the long-term outcome of liver transplantation at a single center.

METHODS

From October 1998 to April 2011, medical records, laboratory data, and pretransplantation lymphocytotoxic CXM results were collected from 1133 consecutive liver transplant recipients.

RESULTS

We performed liver transplantations on 80 (7.1%) patients after a true-positive CXM (t+CXM). The t+CXM group exhibited higher initial aminotransferase levels immediately after transplantation compared with a negative CXM group. However, no significant differences in rejection, biliary or vascular complications, viral disease recurrence, or de novo malignancies were found. Although overall graft and patient survival did not differ between the groups, liver-specific graft survival was inferior in the t+CXM group. It was also found that, in 42 (3.7%) recipients, initially positive results converted to final negative results after the elimination of immunoglobulin M autoantibodies. We defined this subpopulation as a false-positive CXM. Significantly decreased posttransplantation aminotransferase levels with a higher incidence of de novo malignancies were observed in this group compared with negative controls.

CONCLUSION

Our findings demonstrate that t+CXM transplants show increased aspartate aminotransferase and alanine aminotransferase peak immediately after transplantation, which influences liver-specific graft outcomes. Additionally, the presence of circulating immunoglobulin M autoantibodies against recipients' own antigens may be protective in liver grafts. However, this may be a predisposing factor for de novo malignancies.

Implications of a positive crossmatch in liver transplantation: a 20-year review

Whether a positive crossmatch result has any relevance to liver transplantation (LT) outcomes remains controversial. We assessed the impact of a positive crossmatch result on patient and graft survival and posttransplant complications. During a 20-year period, 2723 LT procedures with crossmatch results were identified: 2479 primary transplants and 244 retransplants. The rates of positive B cell and T cell crossmatches were 10.1% and 7.4%, respectively, for primary transplants and 14.6% and 6.4%, respectively, for retransplants (P = 0.049 for a B cell crossmatch). Across all primary transplants, females (P < 0.001) and patients with autoimmune hepatitis (P < 0.001) had greater frequencies of positive crossmatches. There was no effect from race or age. For both primary transplants and retransplants, patient survival and graft survival were not affected by the presence of a positive crossmatch. With respect to posttransplant complications, there were no differences in rejection episodes (hyperacute, acute, or chronic) or technical complications (biliary and vascular) between negative and positive crossmatch groups. However, there were significant differences in the pathological findings of preservation injury (PI) on liver biopsy samples taken at the time of transplantation and within the first week of transplantation (P = 0.003 for B cells and P = 0.03 for T cells). In summary, a positive crossmatch had no significant impact on patient survival or graft outcomes. However, there was a significantly higher incidence of PI in primary LT recipients with a positive crossmatch. This finding is important for a broader understanding of PI, which may include a significant immunological component.

Allosensitization and outcomes in pediatric heart transplantation

BACKGROUND

Allosensitization among children being considered for heart transplantation remains a great challenge. Controversy exists as to the best approach for those with elevated panel-reactive antibody (PRA) titers. We sought to define the association between elevated PRA and outcomes using data from the multi-institutional Pediatric Heart Transplant Study Group.

METHODS

Between January 1993 and December 2008, 3,016 patients (>1 month of age) were listed for heart transplantation. PRA data at listing were available for 2,500 (83%) patients, and 2,237 underwent transplantation with PRA data being available for 1,904 (85%). Because various PRA assays were employed (e.g., cell-based and solid phase) we entered the highest value regardless of methodology.

RESULTS

Among the factors associated with high PRA at transplant were Status 1 at listing, previous sternotomy and prior Norwood procedure. An elevated PRA at listing was associated with higher risk of death while waiting. Of subjects with PRA ≥ 50% only 57% were transplanted by 1 year on the waitlist, as compared with 76% of those with PRA <10%. Waitlist mortality for the highly allosensitized subjects (≥ PRA 50%) was 19% by 12 months. Survival at 1 year after transplantation was significantly lower in those with PRA ≥ 50% versus those with PRA <10% (73% vs 90%, respectively, p < 0.0001). Those with elevated PRA who had a negative prospective crossmatch had no difference in survival compared with those without allosensitization. There was no significant association between PRA levels and time to first rejection or development of coronary allograft vasculopathy.

CONCLUSIONS

Significant allosensitization is associated with more than a 2-fold increased risk of death within the first transplant year. Although prospective crossmatching abrogates the risk of post-transplant mortality, it may contribute to higher pre-transplant attrition due to longer waitlist times. There is a critical need for strategies to minimize the impact of allosensitization and antibody-mediated rejection immediately after transplantation.

Significance of C4d staining in ABO-identical/compatible liver transplantation

Complement degradation product C4d has become an important marker of humoral or antibody-mediated rejection in renal and heart allograft biopsies. Although there have been several reports on the detection of C4d in liver allografts, the significance of C4d in liver transplantation and its relationship with humoral rejection are still not clear. We investigated the frequency and pattern of C4d staining in liver allograft biopsies with reference to preoperative lymphocyte crossmatch tests, which detect donor-reactive lymphocyte antibody. Survival rates at 5 years were 77% for crossmatch-negative patients and 53% for crossmatch-positive patients (P=0.009). In crossmatch-negative patients, reproducible positive staining was obtained in 28 of 86 (33%) biopsies taken within 90 days after transplantation and 33 of 96 (34%) biopsies 90 days or after transplantation. Most C4d staining was observed in the portal areas, and no clear correlation was observed between C4d positivity and histological diagnosis. In crossmatch-positive patients, 9 of 11 (82%) biopsies showed positivity for C4d. C4d stained perivenular areas as well as portal areas. Histology of crossmatch-positive patients included acute rejection and cholangitis, but did not include periportal changes that were seen in humoral rejection in ABO-incompatible liver transplantation. In summary, focal C4d deposition was seen in various types of liver allograft injury and had little clinical impact on crossmatch-negative patients, but extensive C4d staining in crossmatch-positive patients may be associated with humoral rejection and poor graft survival.

Pancreas transplantation in crossmatch-positive recipients

BACKGROUND

Prolonged cold preservation time can unfavorably affect outcome in pancreas transplantation. To reduce this ischemic time, cadaver pancreas grafts, in selected cases, are sometimes transplanted before crossmatch results are known. We report our experience with pancreas transplants in recipients with either current or historically positive T- or B-cell crossmatches.

METHODS

Crossmatch-positive pancreas transplants were identified using a computerized database. T-cell crossmatches were performed using an antihuman-globulin-augmented complement-dependent cytotoxicity (CDC) test; B-cell crossmatches were performed using an extended incubation CDC test. All patients received anti-T-cell induction therapy and either cyclosporine (1987-1993) or tacrolimus-based (1994-2001) immunosuppression. More recent recipients (2000-2001) also received intravenous gamma globulin and postoperative plasmapheresis.

RESULTS

Between October 1, 1987 and March 31, 2001, of a total of 1076 pancreas transplants performed, 59 (5.48%) were crossmatch-positive. Of these, 8 had a current T-cell-positive crossmatch and 15 had a current B-cell-positive crossmatch. One recipient was both current B- and T-positive, and the rest were past B- and/or T-cell positive. One-year pancreas graft survival for current T- and B-cell crossmatch-positive transplants was 63% and 67%, respectively. T- or B-cell crossmatch-negative transplants had a 1-yr survival of 70%. In the T-cell crossmatch-positive group, four grafts are still functioning (follow-up range, 2-12 yr), one patient died with a functioning graft at 4 months, and four grafts failed (one each from pancreatitis, infection, primary nonfunction, and vascular thrombosis). No grafts were lost to rejection. In the B-cell crossmatch-positive group, six grafts are still functioning (follow-up range, 2-11 yr) and nine have failed (four from chronic rejection, three from vascular thromboses, and two from pancreatitis). Crossmatch-positive cases were significantly more likely to be retransplants (70.8%) than crossmatch-negative cases (14.8%, p < 0.0001). In a multivariate analysis, crossmatch positivity did not affect pancreas graft outcome, whereas retransplants had a significant impact on outcome (relative risk 1.84, p < 0.0001).

CONCLUSIONS

(: i) Pancreas transplants performed in the setting of a positive current crossmatch may have long-term function. (ii) With current immunosuppressive protocols, graft loss from hyperacute and acute rejection may be prevented in current crossmatch-positive pancreas transplants. Chronic rejection was only seen in B-cell crossmatch-positive cases. (iii) High rates of technical graft loss in crossmatch-positive cases may reflect a high frequency of retransplants in this group.

Endothelial C4d deposition is associated with inferior kidney allograft outcome independently of cellular rejection

BACKGROUND

Capillary deposition of complement split product C4d has been suggested to be a valuable marker for humoral rejection. In this retrospective study we evaluated the clinical impact of C4d deposition in renal allografts with special emphasis on associations between C4d staining patterns and histological features of acute rejection.

METHODS

One hundred and two allograft biopsies obtained from 61 kidney transplants (1-532 days after transplantation; median 14 days) were examined by immunohistochemistry on routine paraffin sections using a novel anti-C4d polyclonal antibody (C4dpAb).

RESULTS

Fourty-two of 102 biopsies showed endothelial C4d deposits in peritubular capillaries (PTC). Histopathological analysis revealed a significantly lower frequency of positive C4d staining in biopsies with rather than in those without acute cellular rejection defined by the Banff grading schema (P<0.01). For clinical evaluation, patients were classified according to C4d staining in allografts (C4d(PTC) positive in at least one biopsy, n=31 vs C4d(PTC) negative in all biopsies, n=30). C4d(PTC) positive patients had significantly higher serum creatinine levels than C4d negative patients. Even in the absence of morphological evidence for rejection, differences in serum creatinine levels between C4d(PTC) positive and negative recipients were significant (6 months: 2.01+/-0.75 vs 1.41+/-0.27 mg/dl; 12 months: 1.95+/-0.60 vs 1.36+/- 0.34 mg/dl; 18 months: 1.98+/-0.50 vs 1.47+/-0.31 mg/dl; P<0.05). All patients with rejection resistant to conventional therapy (n=4) were in the C4d(PTC) positive subgroup. All recipients with panel reactive antibodies (PRA) >50% (n=8) were C4d(PTC) positive.

CONCLUSIONS

Our data indicate that endothelial C4d deposition is associated with inferior graft outcome. We provide evidence that this immunohistochemical finding and its clinical impact are not associated with morphological signs of cellular rejection.

Introduction of the certificate in transplant coordination in the United Kingdom

Training for transplant coordinators is not mandatory in the United Kingdom, although the United Kingdom Transplant Coordinators Association has provided informal courses since 1988. The authors of this article were responsible for the development of an accredited training program for transplant coordinators in the United Kingdom. Accredited by the University of Central England, the course modules have been run and managed by the Association since 1996. The course consists of 3 modules: Introduction to Transplant Coordination; Interpersonal and Professional Skills for Transplant Coordinators, and Introduction to Research Methods for Transplant Coordinators. Between 1996 and 1999, 64 transplant coordinators (60% of transplant coordinators currently in post) in the United Kingdom have undertaken at least 1 module. The Association feels that the accredited training program means one step further on the road to professional recognition of transplant coordinators in the United Kingdom.