Renal transplantation and a positive serological cross-match

B-Cell crossmatching and kidney allograft outcome in 9031 United States transplant recipients

The predictive power of a positive B-cell crossmatch remains controversial due to the presence of cofactors, such as sensitization and human leukocyte antigen (HLA) mismatch levels. UNOS OPTN/Scientific Registry data were analyzed on 9031 cadaveric kidney graft recipients who were B-cell crossmatched during 1994 and 1995 for graft outcome. This 2-year time period was chosen so that most US transplant recipients in this study would have had a similar regimen of immunosuppression consisting of prednisone, Sandimmune, and azathioprine The two patient groups that were analyzed were B-pos (n = 336) and B-neg (n = 8,695). All T-cell crossmatches were negative. Data analyzed included donor-recipient demographics, sensitization levels, B-cell crossmatch techniques, histocompatibility mismatching, graft rejection incidence, early graft loss, cause of graft failure, and statistical analyses (univariate and multivariate) in primary and repeat graft recipients. Significant factors in both crossmatch groups included pretransplant transfusions, peak and most recent class I PRA levels, a previous kidney graft, histocompatibility mismatching at HLA-A plus -B, urine in first 24 h, and rejection incidence between discharge and 6 months post-transplantation. Class II antibody specificities and panel reactive antibody (PRA) levels were not available from the UNOS database. Fifty-seven percent of 15,896 (1994-1995) transplant recipients (n 9031) were B-cell crossmatched, and 336 of 9031 recipients (3.7%) were transplanted with a B-pos crossmatch. Sixteen percent of B-pos recipients experienced early graft loss (< 6 months) compared with 11% of B-neg recipients (p < 0.001). Both primary and repeat grafts with B-pos crossmatches experienced an increase in rejection incidence (p = 0.023) and early graft loss (p < 0.001). In the sensitized (PRA > 10%) recipient subset (n = 2,789), both primary (n = 93) and regraft (n = 52) recipients with B-pos crossmatches had a higher incidence of early graft loss at 3 months, p < 0.001 and p = 0.016, respectively. HLA-DR mismatch levels in both patient groups were not different (p = 0.109). There was a 68% increase in the odds of 3-month graft loss in B-pos versus B-neg recipients (multivariate logistic regression analysis p = 0.054, 95% confidence interval 0.99-2.85). In conclusion, a B-pos crossmatch in primary and regraft recipients, including a sensitized subset, is predictive of inferior kidney graft outcome.

Current status of immunological monitoring in the renal allograft recipient

With the appropriate combined use of different immune monitoring techniques, it is possible to derive sensitive diagnostic parameters for the transplant surgeon. However, the core biopsy or cytological examination of the graft continues to represent the gold standard for evaluating the specificity and sensitivity of these methods. With the development of newer monoclonal antibodies and a better understanding of the impact of immune processes on the behavior of various activation linked, T cell associated surface antigens, one may be able to secure further valuable information, with enhanced diagnostic and prognostic accuracy.

An investigation of nonhemolytic transfusion reactions

This study was undertaken to document the incidence of immediate, nonhemolytic transfusion reactions and to identify a technique or set of techniques that would best identify the different causes of these reactions. A variety of tests were employed to detect lymphocyte, granulocyte, platelet and anti-IgA antibodies. During this study 26,318 units of blood components were transfused on 5,030 occasions. 191 immediate, nonhemolytic reactions were experienced giving an incidence per unit of 0.73%. Blood specimens from 101 of these patients were investigated along with serum from 57 patients who showed no reaction to transfusion as controls. We show that standard B cell lymphocytotoxicity testing is the technique with which most antibodies can be detected (64% of reactors positive vs. 30% of controls, p less than 0.001). Additional tests did not significantly increase the level of antibody detection.

Histocompatibility in cardiac transplantation with particular reference to immunopathology of positive serologic crossmatch

Cardiac allografting was carried out in 33 patients during the past 2 years. Twenty-one (64%) of the patients are alive and others lived for different periods after transplantation. The number of HLA-AB and HLA-DR antigens matched or mismatched was not significantly different between the surviving and deceased patients. However, 100% (4 of the 4) of the patients with a positive serum crossmatch with donor T lymphocytes are deceased as compared to the 25% (7 of the 28) mortality rate for crossmatch-negative patients. All four of the deceased patients with a positive crossmatch had demonstrable deposition of immunoglobulins in the capillaries of the donor heart at autopsy, whereas no immunoglobulin or fibrinogen deposition was seen in the hearts of crossmatch-negative patients. Three of the four patients with positive crossmatches had sera cytotoxic to lymphocytes of more than 25% of the persons, of a 42 member panel, whereas in the remaining one the serum was cytotoxic to less than 5% of the panel members. In crossmatch-negative patients, the sera were cytotoxic to less than 20% of the panel members with one exception. The relevance of cytotoxic antibodies to lymphocytes of panel members, crossmatch, and tissue deposition of immunoglobulins is discussed.

Successful renal transplantation in patients with T-cell reactivity to donor

A positive crossmatch due to T-cell reactivity against donor cells is considered a strong contraindication to renal transplantation because of the risk of graft loss from rejection. However, the significance of T-cell reactivity before but not at the time of transplantation is unknown. To determine whether transplantation can be successful under these circumstances, graft survival was observed in 15 highly sensitised patients whose T cells were reactive to donor sera before but not at the time of transplantation. All patients have been followed up for at least 1 year post transplant. Immunosuppression was by azathioprine, prednisone, and rabbit antithymocyte sera. 9 (60%) have functioning grafts and a mean serum creatinine of 1.6 mg/dl. Early non-function occurred in 12 patients. One graft was lost to early acute humoral rejection and two other to chronic rejection. 14 of the 15 had a fall in reactivity to a panel of normal lymphocytes before transplant. 4 of the 15 had donor-specific B-cell antibodies at the time of transplantation and 3 of these lost their grafts because of rejection.

Cold lymphocytotoxins: an important cause of acute tubular necrosis occurring immediately after transplantation

Cold-reactive lymphocytotoxins, present in some renal-transplant recipients, may be an important cause of the acute tubular necrosis (ATN) that commonly occurs immediately after transplantation. In a study of transplantation of optimally preserved cadaveric kidneys obtained from heart-beating donors, ATN was found in 10 of 17 recipients with cold antibodies and in only 1 of 21 recipients without such antibodies. Warming of the allograft after completion of anastomosis significantly reduced the incidence of ATN at 18% in recipients with cold antibodies. When pairs of reicpients with cold antibodies were transplanted with identically preserved cadaveric kidneys from single donors ATN was observed only in recipients whose donor kidney was not warmed. ATN may result from antibody-medicated damage to vascular endothelial cells during the brief period when the recipient's blood starts flowing into a "cold" allograft.

Role of humoral presenitization in human renal transplant rejection

A prospective study of 31 cadaveric renal allograft recipients was performed to determine the significance of pretransplant presensitization undetected by the conventional microlymphocytotoxicity crossmatch. Donor-specific humoral presensitization revealed by the antibody-dependent cell-mediated cytotoxicity assay (ADCC) was associated with a high incidence of early graft rejection. Six-month graft survival was 20% in recipients with positive pretransplant ADCC and 75% in ADCC-negative recipients (P < 0.01). Among recipients highly presensitized to a random panel of HLA antigens, donor-specific humoral presensitization detected by chromium-51-release complement-dependent cytotoxicity (51Cr-CDC) was also highly correlated with accelerated rejection (P < 0.05). Pathologic study of the rejected allografts revealed antibody-mediated rejection vasculitis in all recipients. We conclude that humoral presensitization undetected by current conventional methods plays a cardinal role in early renal graft rejection and is a major factor responsible for low cadaveric renal transplant survival. This study suggests that use of the ADCC and 51Cr-CDC as routine adjunctive crossmatch procedures may contribute to improvement in renal transplant survival rates.

Association of MB compatibility with successful intrafamilial kidney transplantation

The MB system is a newly defined system of B-cell alloantigens closely associated with HLA-DR. We assessed the role of MB compatibility in renal transplantation in a retrospective study of 21 patients who had received a kidney transplant from a related donor matched for a single HLA haplotype. One-year transplant survival was closely correlated with the presence of a compatibile MB antigen in the unshared haplotype of the donor: Eight of eight rejected kidneys were obtained from MB-incompatible donors, and 12 of 13 successful transplants were from MB-compatible donors. The association between MB compatibility and allograft acceptance was highly significant (P = 4.4 x 10(-5)), but no significant relation could be demonstrated between transplant survival and donor-recipient compatibility for antigens of the HLA-A, B or DR loci. These findings suggest that match matching for MB may be critical for the selection of donors in intrafamilial kidney transplantation.

Immunological monitoring as a guide to the management of transplant recipients

Immunological monitoring assays are of current value in the management of transplant recipients. These assays allow the pre-transplant quantitation of both donor-recipient histocompatibility and recipient "responder status." In addition, these assays allow the individualization of immunosuppression, permitting a more uniform and effective immunosuppression in the difficult early post-transplant period. Individualized modulation of recipient immune reactivity avoids the documented pitfalls of conventional stereotyped suppression and permits better abrogation of acute rejection responses and lesser rates of serious infections consequent to excessive immune suppression. Immunological monitoring of long-surviving recipients permits early detection of immune reactivity which often culminates in clinical chronic rejection, as well as permits the quantitation of immune facilitory mechanisms (reduced capability to generate anti-donor cytotoxic T cells and/or cellular suppressor mechanisms) that indicate an immune milieu conductive to long-term graft survival. The primary limitations to the more widespread use of immunological monitoring assays at present are the need for more consensual validations of the utility of these assays in different laboratories, more standardization and better controls of techniques, and improvement in the technology of the assays to permit rapid, reproducible, and accurate results with a lesser expenditure of laboratory time and money and greater economy in demands for recipient blood and donor tissue. Finally, immunological monitoring assays are notable for the great promise they offer in terms of immunobiological probes to dissect mechanisms of rejection, mechanisms of graft facilitation, mechanisms of action of immunosuppressive agents, and mechanisms by which empirical technology of recipient pre-treatment may condition the host to better acceptance of an incompatible graft.

Separation of human cells bearing HLA-DR antigens using a monoclonal antibody rosetting method

A technique is described for enriching, from human blood, cells bearing HLA-DR antigens. The method depends on the use of monoclonal mouse antibody which reacts with HLA-DR structures. Cells to which this antibody has bound can be separated after rosetting with bovine erythrocytes coated with anti-mouse immunoglobulin. The cells thus enriched may be used for HLA-DR typing by standard cytotoxicity methods with allogeneic sera.

Results from a new renal transplantation unit

158 kidneys, 9 from living related donors and 149 from cadavers, have been transplanted in the first 42 months of the establishment of a transplant unit at Oxford. Patients' ages ranged from 11 to 56 (mean 35) years. Azathioprine and prednisolone alone were used for immunosuppression, and a minimum-transfusion policy was in operation throughout. After cadaveric transplantation actuarial patient-survival is 70% and 68%, respectively, at the same intervals. 85% of patients who had a functioning graft are fully rehabilitated. Matching for HLA-DR, pregraft blood-transfusions, and the finding that a transplant could be performed in the presence of a positive B-cell crossmatch have proved to be the most significant of the many factors examined both prospectively and retrospectively. The function of the unit is based on dialysis and transplantation for all patients in end-stage renal failure, with transplantation being considered the first line of treatment for patients under the age of 56. The results of transplantation reported here, which have been achieved with conventional immunosuppressive therapy and minimum-transfusion policy, might be considered a standard against which modifications of the practice of renal transplantation can be compared.

Enhancement of human kidney allografts by cold B-lymphocyte cytotoxins

The sera of 233 kidney transplant patients before transplantation were tested by cytotoxicity against a panel of B and T lymphocytes at 5 degrees C and 37 degrees C. The results divided the patients into four groups: those whose sera reacted with B lymphocytes at 5 degrees C; those reacting with B lymphocytes at 5 degrees C and 37 degrees C; those reacting with T lymphocytes at 37 degrees C; and those with no antibodies. The patients with pre-transplant antibodies reactive with B lymphocytes at 5 degrees C had a significantly higher kidney-transplant survival rate at 6 months (70%) and 1 year (65%) than patients who had no antibodies (47% and 46%, respectively). Patients with antibodies reactive at 37 degrees C had a 6-month survival-rate of 38% when reactive against B cells and 43% when reactive against T lymphocytes. The cold cytotoxins were IgM.

Matching for B-cell antigens of the HLA-DR series in cadaver renal transplantation

Stored and fresh lymphocytes from 84 donors and recipients of cadaveric renal allografts have been retrospectively typed for 7 HLA-DR antigens. The match between donor and recipient was graded as 2, 1, or 0 identities. Graft function was assessed by (i) failure or success at 3 months, (ii) serum-creatinine at 3 and 6 months, and (iii) the number of rejection episodes occurring within 3 months. All 4 recipients with 2 identities had good 3-month function, and all are still functioning at 5--19 months. Recipients with 1 identity had both a higher success-rate and better quality of function than those with 0 identities. Although the differences do not reach significance, a continuing prospective study of HLA-DR matching is justified, with particular emphasis on performing transplants where two DR antigens are shared between donor and recipient.

Renal transplantation and B-cell cross-matches with autoantibodies and alloantibodies

Of 51 cadaveric kidneys transplanted between June, 1976, and June, 1977, 18 were transplanted in the presence of a positive cross-match against the donor's B lymphocytes. 11 of these positive cross-matches were due to alloantibodies and 7 due to autoantibodies. Autoantibodies were defined not only on the basis of autoreactivity with B lymphocytes but also by their absent or restricted reactivity with lymphocytes from patients with chronic lymphocytic leukaemia. Transplants in 8 of 11 patients with a positive alloantibody-B-cell cross-match and in 6 of 7 patients with a positive autoantibody-B-cell cross-match were successful at 3 months. These success-rates were no different from those found in patients with a negative B-cell cross-match. Thus, renal allografts may be performed with a reasonable assurance of success in the presence of a positive B-cell cross-match whether due to autoantibodies or to alloantibodies.

Autoantibody against B lymphocytes

The sera of 20 out of 99 (20%) normal males and females were shown to have antibodies that kill their own B lymphocytes. The sera were specifically cytotoxic to B lymphocytes and not T lymphocytes. Allogeneic B lymphocytes were also killed by these autocytotoxins. Maximum killing of B lymphocytes occurred when the incubation temperature in serum was 5 degrees C and complement incubation temperature was 20 degrees C. Under these cold conditions, some sera reacted up to a dilution of 1/16. These results suggest that positive B-lymphocyte crossmatches found in kidney transplantation do not detect alloantibodies. Since the B-cell autoantibodies tend to appear at the time of immunisation, their role as autoregulators of the antibody response is an intriguing possibility.