Positive Lymphocyte Cross-match Research Articles

Human leukocyte antigen compatibility and lymphocyte cross-matching play no significant role in the current adult-to-adult living donor liver transplantation.

The impact of human leukocyte antigen (HLA) compatibility and positive lymphocyte cross-match (LCM) on organ transplantation is well-recognized particularly in kidney and heart transplantation; however, it is still debatable in liver transplantation (LT). So, the aim of this study was to evaluate the impact of HLA mismatch and positive LCM on the outcome of LT. We retrospectively analyzed the data of all adult recipients who underwent living donor LT at our institute between January 2010 and July 2016. We excluded all ABO blood group incompatible LDLT patients and patients with incomplete data regarding HLA genotyping (n=134). The type and degree of HLA-A, HLA-B, HLA-C, HLA-DR, HLA-DQ mismatch and LCM were assessed in each donor-recipient pair and their relationship to the occurrence of rejection, CMV infection and graft survival was evaluated. A higher percentage (>50%) of donor-recipient pairs had 1 HLA mismatch at each locus in the host-vs-graft direction and seventeen recipients (13%) had positive LCM. Human leukocyte antigen mismatch and positive LCM were not correlated with increased incidence of acute rejection (P=.37, P=.6, respectively), CMV infection post-transplant (P=.52, P=.76, respectively), or graft failure (HR 1.22, P=.68 and HR 1.73, P=.34, respectively). Positive LCM and HLA mismatches did not affect the overall graft survival after adult-to-adult LDLT and should not be considered as contraindications for liver transplantation.

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Abstract Aim It is generally accepted that a positive cytotoxic lymphocyte crossmatch (CDC-XM) is a contraindication for transplantation. However the assay is insensitive for detecting low levels of alloantibodies. The Flow cytometry crossmatch (IgG-FXM) is very sensitive but cannot differentiate HLA complement fixing antibody (CFAb) from non-CFAb and its clinical significance is still controversial. Based on the clinical relevance of CDC, we have successfully developed a new Flow Cytometry C1q crossmatch (C1q-FXM) to specifically detect Methods Donor PBMCs (0.1x 10 6 ) were incubated with 30 ul serum and CD3-PerCPCy5.5, CD19-FITC and SAPE-Bio-C1q for 30 minutes. After washing, the cells were collected and analyzed on a Canto-II flow cytometer. The PE fluorescence intensity on the T and B lymphocytes is proportionate to the amount of C1q fixed on the cell surface and reflects the complement fixing capability of DSA. CFAb with high sensitivity. Results A total of 120 XMs (66 Tc-XM, 54 Bc-XM) were performed in parallel using CDC-XM, IgG-FXM, and C1q-FXM. C1q-FXM correlated well with CDC-XM but has higher sensitivity. The concordance of two crossmatches was 88% (P Conclusion The newly developed C1q-FXM combines the advantage of the CDC-XM for detecting CFAb with the high sensitivity of the IgG-FXM assay. It can replace the traditional CDC-XM.

Mesenchymal stem cell transfusion for desensitization of positive lymphocyte cross‐match before kidney transplantation: outcome of 3 cases

Donor specific antibodies (DSA) and a positive cross-match are contraindications for kidney transplantation. Trials of allograft transplantation across the HLA barrier have employed desensitization strategies, including the use of plasmapheresis, intravenous immunoglobulins, anti-B-cell monoclonal antibodies and splenectomy, associated with high-intensity immunosuppressive regimens. Our case 1 report suffered from repeatedly positive lymphocyte cross match after 1st renal transplantation. Graft nephrectomy could not correct the state of sensitization. Splenectomy was done in a trial to get rid of the antibody producing clone. Furthermore plasmapheresis with low dose IVIG could not as well revert the state of sensitization for the patient. About 50 millions donor specific MSCs were injected to the patient. MSCs transfusion proved to be the only procedure which could achieve successful desensitization before performing the second transplantation owing to their immunosuppressive properties. This case indicates that DS-MSCs is a potential option for anti-HLA desensitization. In cases 2 and 3 IV DS-MSCs transfusion was selected from the start as a successful line of treatment for pre renal transplantation desensitization to save other unnecessary lines of treatment that were tried in case 1.

Donor Specific Mesenchymal Stem Cells MSCs Transfusion for Desensitization of Resistant Positive Donor Specific Lymphocyte Cross Match and Reduction of Panel Reactive Antibodies PRA. Report of 4 Cases.

Sensitization to HLA antigens may be induced by previously administered blood products, pregnancy, or prior transplantation. It represents an important barrier to renal transplantation. Procedures adopted to achieve desensitization include single high dose IVIG or low dose IVIG in combination with antibody reduction via plasmapheresis with or without splenectomy. Mesenchymal stem cells (MSCs) among their properties have an important imuno-modulatory effect and have been shown to inhibit anti-HLA allo-antibody production in vitro. Four cases were given 7 - 10 million donor specific MSCs infused intravenously in 2 divided doses 1 week apart. After initial increase in the positivity of the cross match, it turned negative in 2 to 4 months period with reduction of the percent of PRA and were subsequently successfully transplanted. Donor specific MSCs represents a therapeutic option for desensitization of positive lymphocyte cross match.

Donor Specific Mesenchymal Stem Cells MSCs Transfusion for Desensitization of Resistant Positive Donor Specific Lymphocyte Cross Match and Reduction of Panel Reactive Antibodies PRA. Report of 4 Cases.

Sensitization to HLA antigens may be induced by previously administered blood products, pregnancy, or prior transplantation. It represents an important barrier to renal transplantation. Procedures adopted to achieve desensitization include single high dose IVIG or low dose IVIG in combination with antibody reduction via plasmapheresis with or without splenectomy. Mesenchymal stem cells (MSCs) among their properties have an important imuno-modulatory effect and have been shown to inhibit anti-HLA allo-antibody production in vitro. Four cases were given 7 - 10 million donor specific MSCs infused intravenously in 2 divided doses 1 week apart. After initial increase in the positivity of the cross match, it turned negative in 2 to 4 months period with reduction of the percent of PRA and were subsequently successfully transplanted. Donor specific MSCs represents a therapeutic option for desensitization of positive lymphocyte cross match.

Current perspectives to overcome a positive crossmatch in living donor renal transplantation*

Transplantation of a living donor kidney is in general the best treatment option for patients with end-stage renal disease. Two major advantages as compared to transplantation with a deceased donor kidney are the avoidance of waiting time and the superior results in terms of renal function and graft survival. In some patients who are lucky enough to have a person in their neighborhood who are willing to donate a kidney, the transplantation cannot be performed directly because there is ABO blood type incompatibility between donor and recipient, or because of a positive lymphocyte crossmatch, based on the presence of donor-specific antibodies. During recent years, several strategies have been developed to enable transplantation in these cases. A first approach is to use a living donor kidney exchange program, which can result in successful matches in more than half of the crossmatch-positive couples [1]. With the incorporation of kidneys from nondirected, anonymous donors in such an exchange program, domino-paired chains of transplantations can be set up, which end with the transplantation of a living donor kidney to a recipient from the waiting list [2]. However, for a substantial number of recipients, these exchange programs do not result in a successful donor–recipient match. In these cases, desensitization strategies to reduce the titer of ABO blood group antibodies or anti-HLA antibodies can be employed. Desensitization techniques are based on the extracorporeal removal of antibodies, treatment with intravenous immunoglobulins, and on immunosuppressive therapy. Since these procedures carry additional risks for the transplant recipient, desensitization treatment should ideally be reserved for recipients who cannot be served with a donor kidney after several rounds of matching in a (multicenter) exchange program. Unfortunately, kidney exchange programs are not allowed by legislation in every country. In this issue of Transplant International, Morath et al. present the results of living donor kidney transplantation in nine crossmatch-positive patients with peritransplant immunoadsorption (IA) and induction therapy with the anti-CD20 antibody rituximab [3]. Three patients also underwent pretransplant plasmapheresis. In one additional patient with a negative crossmatch but high titers Correspondence L. B. Hilbrands, Department of Nephrology, Radboud University Nijmegen, PO Box 9101, 6500, HB Nijmegen, The Netherlands. E-mail: l.hilbrands@nier.umcn.nl

Paired exchange kidney donation in India: a five-year single-center experience

Paired exchange kidney donation (PKD) is an evolving strategy for overcoming the barriers that confront patients with end-stage renal disease, when the only living potential donors who are willing to donate to them are deemed to be unsuitable as donors for them owing to an incompatibility of blood type, of HLA cross-match, or of both. In the PKD, the incompatibility problems with two donor recipient pairs can be solved by exchanging donors. Although PKD is increasing worldwide, we in India have not nearly reached the estimated potential of this modality. Herein, we have reported our results with a living donor exchange program in past 5 years. Between March 2006 and June 2011, we performed 44 living PKD transplantations. All donor and recipient procedures were performed successfully. ABO incompatibility or positive lymphocyte cross-match were found in 20 pairs and 2 pairs, respectively. The mean recipient age was 42.5 years (range 33-59 years). The mean donor age was 38 years (range 31-56 years). At a median follow-up of 33 months (range 1-59 months), graft survival rate was 100 %. All patients have functioning grafts with a median serum Creatinine level of 1.13, 1.5, and 1.35 mg/dl at 3 month, 1 year, and 3 years, respectively. One patient died after 4 month of transplant due to pneumonitis with sepsis. Allograft dysfunction was not seen in any of the recipients. The PKD transplantation is a viable procedure medically and economically, which can be promoted in centers with a low deceased donor transplantation rate and a high number of incompatible related donors. We achieved excellent graft outcome by using the PKD transplantation program as an option to reduce the donor organ shortage.

Predictive Value of Donor Specific Antibody Measured by Luminex Single Antigen Assay for Antibody Mediated Rejection after Kidney Transplantation

Background: Luminex panel reactive antibody (PRA) is a method that is well known for its high sensitivity and specificity. By using a single antigen assay, the presence or absence of donor specific antibody (DSA) can be determined and its strength can be quantified in terms of the mean fluorescence intensity (MFI). In this study, we analyzed the correlation between the pre-transplant PRA and DSA measured by the Luminex method and the post-transplant clinical features after kidney transplantation. Methods: A total of 123 pre-transplant sera samples from kidney transplanted patients were tested. Luminex-PRA identification tests were performed using a Luminex fluoroanalyzer and a LifeCodes class I, II ID Kits. Single antigen assay by the Luminex method was used for detecting DSA and its MFI. Results: The positive Luminex-PRA group included more highly-sensitized patients such as women, patients with a previously positive lymphocyte cross match test and patients who were undergoing retransplantation. There was no correlation between the acute rejection rate and positive PRA on the Luminex-PRA. However, pretransplant DSA detected by the single antigen assay was significantly associated with episodes of antibody mediated rejection (P=0.047, OR=10.2), and DSA with higher MFI values (MFI≥3,000) was associated with antibody mediated rejection (P=0.023). Conclusions: Although pre-transplant positive PRA was not correlated with acute rejection episodes, the DSA measured by the Luminex single antigen assay seems to have a predictive value for post-transplant antibody mediated rejection.

Does a positive lymphocyte cross-match contraindicate living-donor liver transplantation?

There is still no consensus on the importance of lymphocyte cross-matching (LCM) in the field of living-donor liver transplantation (LDLT). LCM examinations are routinely performed before LDLT, and the results of complement-dependent cytotoxicity were used in this study. A total of 1157 LDLT cases were evaluated. The recipients were divided into four groups based on the LCM and ABO compatibilities: (1) negative LCM and identical/compatible ABO; (2) negative LCM and incompatible ABO; (3) positive LCM and identical/compatible ABO; and (4) positive LCM and incompatible ABO. The diagnosis of antibody-mediated rejection (AMR) was made based on the clinical course, immunological assays and histopathological findings. C4d immunostaining was added if AMR was suspected. The LCM-positive LDLT recipients showed significantly poorer outcomes than the LCM-negative recipients. Among the LCM-positive recipients, 44.1% of recipients eventually died and 85.2% of recipients revealed positive C4d findings. The survival rate of LCM-positive and ABO-incompatible group was 0.50. The survival days were compared with the LCM-negative and ABO-identical/compatible group, and the LCM-positive and ABO-identical/compatible group clearly showed early death after LDLT, although the ABO-incompatible groups did not show significant. The factors of age, disease, pre-transplant scores, LCM, ABO compatibility and graft-recipient weight ratio showed statistical significance in multivariate analysis for important factors of LDLT outcomes. However, the LCM and ABO compatibilities had no synergetic effects on the LDLT survival. HLA antigens are more widely expressed than ABO antigens, and advanced immunological strategies must be established for LCM-positive LDLT as well as for ABO-incompatible LDLT.

Living donor paired-kidney exchange transplantation: A single institution experience

Introduction:Paired-kidney exchange (PKE) is used in western countries to increase donor pool. In India, there are not many centers involved in PKE program. We present 10 years of this experience and outcome of the recipients.Materials and Methods:Between year 2000 and 2009, 34 transplants with PKE were performed. All donors were live related, and permission from Authorization committee(s) from one or more states was obtained prior to transplantation. Both donor and recipient surgeries were carried out simultaneously in all cases at a single institution. Last 10 donors were offered laparoscopic donor nephrectomy and all other previous donors were operated by open surgery.Results:Five donor–recipient pairs were from the state of Rajasthan, one from Madhya Pradesh, and all others from Gujarat. ABO incompatibility between donor and recipient was present in 12 pairs and positive lymphocyte cross-match in 5 pairs.Conclusion:Paired-kidney-exchange transplantation expands donor pool and total number of transplantation.

In-hospital mortality in adult recipients of living donor liver transplantation: Experience of 576 consecutive cases at a single center

Adult living donor liver transplantation (LDLT) was developed against the background of a scarcity of deceased donors and has a number of disadvantages leading to in-hospital mortality, such as marginal donors and grafts and recipients suffering from severe conditions. We have thus developed surgical and medical innovations to overcome these disadvantages. The present study analyzes the causes of death and factors affecting in-hospital mortality in adult recipients of LDLT. Between November 1994 and December 2007, 576 consecutive adult patients underwent LDLT at a single medical center. Overall in-hospital mortality was 18.9%. The peak rate was 55.6% in 1996, and the rate gradually decreased thereafter to 4.4% in 2007. The most frequent cause of death was infection (62.5%), which was followed by rejection (15.7%) and nonseptic multiple-organ failure (8.9%). Being intensive care unit-bound before the operation, ABO blood type incompatibility, an absence of postoperative enteral nutrition, and a Model for End-Stage Liver Disease score of 25 or higher were independent risk factors for in-hospital mortality. In ABO-identical and ABO-compatible cases, retransplantation and a positive lymphocyte crossmatch test were additional independent risk factors. In conclusion, even aggressive efforts, preoperative conditions such as being intensive care unit-bound, a high Model for End-Stage Liver Disease score, retransplantation, and a positive lymphocyte crossmatch test are still risk factors. Enteral nutrition could be a promising strategy to improve adult LDLT.

Efficacy of a Negative Conversion Trial and Subsequent Living Donor Kidney Transplant Outcome in Recipients with a Positive Lymphocyte Crossmatch

Background: Patients with a positive lymphocyte crossmatch (LCX) do not undergo kidney transplantation. In such patients, a negative conversion protocol consisting of intravenous immunoglobulin (IVIG), plasmapheresis, and potent immunosuppressant is one of the options for transplantation. Methods: 14 patients who showed a positive LCX with living donors underwent a trial of negative conversion between January 2002 and July 2007. Plasmapheresis was performed every other day, up to 6 times maximum. IVIG was infused after plasmapheresis, with a total dose of 500 mg/kg divided over 6 days. Kidney transplantation was performed immediately after negative conversion. Anti-thymocyte globulin (ATG) or OKT3 induction therapy was used with the combination of tacrolimus, mycophenolate mofetil, and prednisone in the perioperative period. Results: Negative conversion of LCX was achieved in 13 of 14 patients (92.9%). Transplantations were performed successfully in these 13 patients without hyperacute rejection. Four recipients developed acute rejection, which was well controlled by steroid pulse therapy. During the follow-up periods of 45.4 ± 22.0 months, all recipients except 1 showed excellent graft function. Conclusion: Selected patients with a positive LCX can undergo successful transplantation using plasmapheresis, IVIG, and potent immunosuppressants. Recipients with negative conversion of LCX showed acceptable posttransplant results.

Exchange Living-Donor Kidney Transplantation: Merits and Limitations

The shortage of donor organs is one of the major barriers to transplantation worldwide. After the success of the direct exchange donor (swap) program in Korea since 1991, we have developed a swap-around program. However, reports on the long-term outcomes of exchange donor programs are scarce. From September 1995 to September 2006, we performed 1193 cases of renal transplantation, including 398 cases from living-unrelated donors. The living-unrelated donors included 129 exchange donors and 269 nonexchange donors. We compared the outcomes of the exchange program with that of the nonexchange program, and examined the merits and limitations of the exchange program. The reasons for the exchange program were ABO incompatibility (n=84, 65.1%), human leukocyte antigen mismatching beyond our criteria (n=39, 30.2%), or positive lymphocyte crossmatch (n=6, 4.7%). The overall 10-year graft survival (86.3%) of exchange transplantation was comparable with that of nonexchange (82.3%) or one- haplotype matched living-related (81.2%) transplantation (P=0.2994). In multivariate analysis, exchange versus nonexchange donors did not affect graft survival. The proportion of blood-type O donors was much lower in the exchange group (29.5%) than in the nonexchange group (42.4%; P=0.026). Blood-type O kidneys were preferentially allocated to blood-type O recipients (78.9%) in the exchange group as compared with the nonexchange group (54.4%; P=0.007). We achieved excellent outcomes by using a donor exchange program as an option to reduce the donor organ shortage. However, the exchange donor program has no added benefit for blood-type O recipients.

Peri-operative Alemtuzumab (Campath-1H) and Plasmapheresis for High-PRA Positive Lymphocyte Crossmatch Heart Transplant: A Strategy to Shorten Left Ventricular Assist Device Support

Patients on a left ventricular assist device (LVAD) often have a high level of panel-reactive antibodies (PRA). Conventional therapy is to await a heart from a negative prospective-crossmatch donor. We transplanted three high-PRA patients with non-crossmatched hearts, using intra- and post-operative plasmapheresis and long-term T-/B-/plasma-cell therapy with alemtuzumab. Three highly sensitized patients (70%, 94% and 96% T-PRA; 63%, 24% and 73% B-PRA) were transplanted after 29, 187 and 94 days LVAD support. The first patient (Case 1) had an erroneous prospective negative crossmatch (due to an outside laboratory's use of the wrong patient's serum) with immediate allograft dysfunction. The correct serum showed a strongly positive crossmatch; plasmapheresis followed by alemtuzumab (20 mg intravenously) shortly after arrival in the ICU resulted in rapid hemodynamic improvement. Encouraged by this success, the next two patients (Cases 2 and 3) underwent LVAD explant and heart transplant with the next available ABO-identical, non-crossmatched donors, using plasmapheresis on bypass immediately before heart implant and alemtuzumab 20 mg intravenously upon ICU arrival, with uneventful courses. All three patients had positive retrospective T- and B-cell crossmatches. Maintenance immunosuppression consisted of cyclosporine and routine prednisone taper, with plasmapheresis as needed (Patient 1, x10; Patient 2, x5) based on diastolic dysfunction. Mycophenolate mofetil was started as a third agent several months post-transplant. Patients are presently New York Heart Association (NYHA) Class I at 26, 16 and 13 months post-transplant. In this small series with follow-up, immediate antibody removal with plasmapheresis, combined with alemtuzumab, a long-acting antibody to CD52 (expressed on T, B and some plasma cells), appears effective in allowing transplantation in sensitized, positive crossmatch recipients. Expanded use of this strategy could shorten LVAD support in many sensitized patients.

274: Thymoglobuline induction therapy creates excellent long-term outcome of patients with positive lymphocyte crossmatch after cardiac transplantation

The effect of pretransplant sensitization on outcome after cardiac transplant has been controversial. Positive lymphocyte crossmatch (LCM) has been associated with with increased incidence of early and severe allograft rejection, vasculopathy and decreased survival. The aim of this study was to analyse outcome of cardiac transplant patients with positive LCM undergoing thymoglobuline induction therapy.

THYMOGLOBULINE INDUCTION THERAPY CREATES EXCELLENT LONG-TERM OUTCOME OF PATIENTS WITH POSITIVE LYMPHOCYTE CROSSMATCH AFTER CARDIAC TRANSPLANTATION

P641 Aims: The effect of pretransplant sensitization on outcome after cardiac transplant has been controversial. Positive lymphocyte crossmatch (LCM) has been associated with with increased incidence of early and severe allograft rejection, vasculopathy and decreased survival. The aim of this study was to analyse outcome of cardiac transplant patients with positive LCM undergoing thymoglobuline induction therapy. Methods: A total number of 341 cardiac transplant patients underwent LCM since 1995. All patients received thymoglobuline induction therapy (2mg/kg/d for 3-7 days). maintenance immunosuppression consisted of calcineurinantagonists (Cyclosporine or tacrolimus), antiproliferative therapy (azathioprine or mycophenolate) and low dose steroids. Patients were divided into two groups (negative LCM, positive LCM) and were analysed for survival, rejection incidence and development of graft-vasculopathy. Results: A total of 36 patients (11%) showed a positive LCM. Patients in both groups were similar on regard to age, sex, diagnosis, previous cardiac operations, retransplantation and implantation of an assist device. There was a significantly higher number of patients with pretransplant PRA [gt]10% in the LCM pos. group (19% vs 8%, p=0.04). One-year (pos:83% vs neg: 83%) and eight year (71% vs 72%) survival were similar between the two groups. Freedom from rejection was also similar (92% vs 90%). Incidences of overall (any changes) and severe ([gt]50% stenosis) graftvasculopathy were similar and low in both groups. (overall: 25% vs 20%; severe: 14% vs 5%). Conclusions: Thymoglobuline induction therapy in patients transplanted across a positive LCM results in similar good outcome as in unsensitized patients.

PANCREATIC TRANSPLANTATION IN ABDOMINAL VISCERAL RECIPIENTS: INDICATIONS, IMMUNOGENICITY AND FUNCTIONAL OUTCOME

O380 Aims: With the recent evolution of intestinal transplantation, the pancreas has frequently been transplanted en-bloc with intestine, liver and other abdominal viscera. On the contrary to combined pancreas-kidney and solitary pancreas transplantation, the gland is commonly included in the visceral graft for non-diabetic indications. The objective of this report is to identify the common indications for the procedure and it’s potential impact on the current United Network of Organ Sharing (UNOS) pancreatic transplant coding system and database. The immunogenicity and functional survival of the pancreatic gland transplanted en-bloc with the other abdominal visceral organs will also be addressed. Methods: Between May 2 and November 3, 2003, the whole pancreatic gland was transplanted en-bloc in 78 (32%) of 246 consecutive primary cadaveric abdominal visceral transplants. The pancreas was combined with: intestine only (n=4), stomach and intestine (n=14), liver and intestine (n=28), and stomach, intestine and liver (n=32). The indications for pancreatic transplant were technical (n=48), vascular thrombosis (n=18), gastrointestinal tumors (n=9), diabetes (n=2), and trauma (n=1) with 75 (96%) of the patients not previously diabetic. All grafts were ABO identical except one, but HLA match was random with positive lymphocyte cross-match in 13 (17%). The intestine of 61 allografts was irradiated with a single dose of 7.5 Gy and adjunct donor bone marrow was given in 53 recipients. Tacrolimus-prednisone based immunosuppression was used for 37 transplants with cyclophosphamide or daclizumab induction in 23. The remaining 41(53%) recipients were enrolled in a tolerogenic protocol with rATG/alemtuzumab pretreatment and post-transplant tacrolimus monotherapy. Results: Actuarial patient survival was 81% at 1 year and 77% at 5 years with pancreatic functional survival rates of 76% and 62%, respectively. The causes of pancreatic graft loss were related to loss of the visceral graft or patient death because of opportunistic infections and/or intestinal rejection. Despite patient complexity, one year survival has recently improved (91%) due to technical innovations, early viral detection, allograft immune-modulation and recipient pretreatment. With antibody pretreatment, 50% of recipients were on spaced doses of tacrolimus. Acute and chronic rejection of the pancreas was significantly less compared to intestine or liver with an incidence of 6% and 1%, respectively. Conclusions: En-bloc pancreas transplantation is commonly indicated for previously non-diabetic patients in need of abdominal visceral transplantation. The gland is immune-protected by the concomitantly transplanted organs. Accordingly, the current UNOS coding system and pancreatic transplant data registry should be modified for logistic reasons and accurate scientific representation of this unique population.

Evolution of HLA antibody detection: technology emulating biology.

New technological advances in the field of histocompatibility have provided an approach to systematically address the specificity of positive lymphocyte crossmatches. These approaches can now confirm whether a positive crossmatch is (or is not) due to class I and/or class II antibodies directed against donor HLA antigens. The information gained from the application of these sensitive and specific technologies can be used to predict crossmatch results for highly sensitized patients. In summary, these emerging technologies have provided the tools to reliably determine the clinical relevance of a positive lymphocyte crossmatch.

Sensitisation to Swine Leukocyte Antigens in Patients with Broadly Reactive HLA Specific Antibodies

We have previously shown that IgG HLA specific antibodies in the sera of highly sensitised patients awaiting renal transplantation can cross-react with swine leukocyte antigens (SLA). In this study we determined the frequency of patient serum IgG HLA specific antibody binding to a porcine lymphocyte panel and the likelihood of locating a cross-match negative pig donor for sensitised patients. Serum samples (n = 82) were obtained from 35 sensitised [current IgG panel reactive antibodies (PRA) > 10%] and seven nonsensitised patients awaiting renal transplantation at Addenbrooke's Hospital, Cambridge, UK. Fifty sera had IgG HLA specific PRA of 11–84%, 20 had IgG PRA of > 84% and 12 had 0% PRA (negative controls). Sera were absorbed with porcine erythrocytes to remove xenoreactive natural antibodies and tested for cross-reactive IgG HLA specific antibody binding by flow cytometry against a panel of porcine lymphocytes obtained from 23 human decay accelerating factor (hDAF) transgenic pigs. A total of 1884 cross-match combinations were tested and 369 (20%) gave a positive porcine lymphocyte cross-match. For sera from sensitised patients with IgG PRA (11–64%), only 6 of 805 (0.75%) cross-match tests were positive. In contrast, for sera from patients with high IgG PRA (> 64%), 363 of 805 (45%) cross-match tests were positive (p < 0.0001). There was no difference in the frequency of positive cross-matches between patient sera with IgG PRA 65–84% and highly sensitised patient sera with IgG PRA 85–100% [156/345 (45%) vs. 207/460 (45%)]. This study demonstrates that only patient sera with broadly reactive IgG HLA specific PRA (> 64%) cross-react with porcine lymphocytes. If future clinical trials of xenotransplantation are undertaken, it may be of value to select a cross-match-negative pig organ donor for such patients.

In-vitro- und In-vivo-Effekte polyvalenter Immunglobuline bei Patientinnen mit rezidivierenden Spontanaborten und antipaternalen non-HLA-Antikörpern - In vitro and in vivo Effects of Polyvalent Imunoglobulins in Patients With Recurrent Spontaneous Abortion and Antipaternal Non-HLA Antibodies -

Fragestellung: Eine Gruppe von Patientinnen mit rezidivierenden Spontanaborten (RSA) produziert zytotoxische antipaternale Antikörper, die nicht gegen klassische HLA-Moleküle gerichtet sind und mit Trophoblasten kreuzreagieren. In vivo und in vitro lässt sich die Konzentration dieser antipaternalen non-HLA-Antikörper durch gepoolte polyvalente Immunglobuline signifikant reduzieren. Es wurde untersucht, ob RSA-Patientinnen mit antipaternalen Antikörpern von einer Therapie mit intravenösen Immunglobulinen (i.v. IgG) profitieren könnten.