Olivia Shaw

The clinical spectrum of de novo donor-specific antibodies in pediatric renal transplant recipients

The development of donor‐specific HLA antibodies (DSA) is associated with worse renal allograft survival in adult patients. This study assessed the natural history of de novo DSA, and its impact on renal function in pediatric renal transplant recipients (RTR). HLA antibodies were measured prospectively using single‐antigen‐bead assays at 1, 3, 6 and 12 months posttransplant followed by 12‐monthly intervals and during episodes of allograft dysfunction. Of 215 patients with HLA antibody monitoring, 75 (35%) developed DSA at median of 0.25 years posttransplant with a high prevalence of Class II (70%) and HLA‐DQ (45%) DSA. DSA resolved in 35 (47%) patients and was associated with earlier detection (median, inter‐quartile range 0.14, 0.09–0.33 vs. 0.84, 0.15–2.37 years) and lower mean fluorescence intensity (MFI) (2658, 1573–3819 vs. 7820, 5166–11 990). Overall, DSA positive patients had more rapid GFR decline with a 50% reduction in GFR at mean 5.3 (CI: 4.7–5.8) years versus 6.1 (5.7–6.4) years in DSA negative patients (p = 0.02). GFR decreased by a magnitude of 1 mL/min/1.73 m2 per log10 increase in Class II DSA MFI (p < 0.01). Using Cox regression, independent factors predicting poorer renal allograft outcome were older age at transplant (hazard ratio 1.1, CI: 1.0–1.2 per year), tubulitis (1.5, 1.3–1.8) and microvasculature injury (2.9, 1.4–5.7). In conclusion, pediatric RTR with de novo DSA and microvasculature injury were at risk of allograft failure.

Detection of HLA-specific IgG antibodies using single recombinant HLA alleles - The monoLISA assay

BACKGROUND Because of the presence of confounding antigens, the assignment of HLA antibody specificity is difficult in highly sensitized patients, and the definition of an acceptable HLA mismatch requires a significant workload per patient. We describe a new ELISA method, monoLISA, for detection of immunoglobulin (Ig)G HLA antibody using single recombinant HLA class I monomers bound to microtiter plates. METHODS HLA-A2 and -B8 monomers were synthesized and used as screening targets for 85 sera from renal patients. The sera contained various IgG and IgM HLA-specific antibodies, including anti-A2 and anti-B8,defined in a conventional complement-dependent cytotoxicity test (CDC). Investigations were performed to determine possible effects on antibody binding of differential monomer peptide presentation as well as lack of glycosylation. RESULTS A good correlation was found between CDC-defined specificities and the reactivity observed with HLA monomers. MonoLISA attained means of 100% sensitivity and 92.5% specificity compared with CDC. Neither the presence of different peptides, nor the absence of glycosylation of the monomer affected the ability of monoLISA to detect antibody. CONCLUSION This study demonstrates that the mono-LISA method for HLA antibody detection is valid. Because this has the potential to reduce the work involved in screening sensitized patients awaiting transplantation for HLA antibodies, resources aimed at increasing the number of constructed monomers would be well targeted.

Incidence and Outcome of C4d Staining With Tubulointerstitial Inflammation in Blood Group-incompatible Kidney Transplantation.

Background The last Banff 2013 report recognizes acute/active antibody-mediated rejection (ABMR) and C4d staining without evidence of rejection. The goal of our study was to analyze the incidence of C4d deposition after ABO-incompatible transplantation and assess outcomes in patients with ABMR, C4d staining without evidence of rejection (all acute Banff scores = 0), and C4d staining with tubulointerstitial inflammation (i > 0 with or without tubulitis). Methods Three-months ‘For cause’ or protocol biopsies in 50 ABO-incompatible patients were rescored and were correlated with clinical outcomes and antibody titres. Results Active/acute ABMR was found in 23 patients (46%), C4d staining without evidence of rejection in 7 patients (14%), C4d staining with tubulointerstitial inflammation in 6 patients (12%), tubulointerstitial inflammation in 6 patients (12%), and no evidence of rejection in 8 patients (16%). Patients with active/acute ABMR had a 3-month estimated glomerular filtration rate (median,: 43 mL/min) lower than patients with no evidence of rejection (median, 61 mL/min; P = 0.01). However, after 3 months, a progressively declining estimated glomerular filtration rate was observed more frequently in patients with C4d staining and tubulointerstitial inflammation when compared to patients with no evidence of rejection (100% vs 25%, P = 0.03). Finally, independently of C4d status, interstitial inflammation occurred more frequently in patients with a pretransplant ABO antibody titre higher than 16 and/or posttransplant ABO antibody increase. Conclusions Whereas isolated C4d deposition and isolated interstitial inflammation appear to be benign lesions, C4d deposition in association with interstitial inflammation is the biopsy finding most strongly associated with the development of chronic graft dysfunction.

Difference in outcomes after antibody-mediated rejection between abo-incompatible and positive cross-match transplantations.

Graft survival seems to be worse in positive cross‐match (HLAi) than in ABO‐incompatible (ABOi) transplantation. However, it is not entirely clear why these differences exist. Sixty‐nine ABOi, 27 HLAi and 10 combined ABOi+HLAi patients were included in this retrospective study, to determine whether the frequency, severity and the outcome of active antibody‐mediated rejection (AMR) were different. Five‐year death‐censored graft survival was better in ABOi than in HLAi and ABOi+HLAi patients (99%, 69% and 64%, respectively, P = 0.0002). Features of AMR were found in 38%, 95% and 100% of ABOi, HLAi and ABOi+HLAi patients that had a biopsy, respectively (P = 0.0001 and P = 0.001). After active AMR, a declining eGFR and graft loss were observed more frequently in HLAi and HLAi+ABOi than in ABOi patients. The poorer prognosis after AMR in HLAi and ABOi+HLAi transplantations was not explained by a higher severity of histological lesions or by a less aggressive treatment. In conclusion, ABOi transplantation offers better results than HLAi transplantation, partly because AMR occurs less frequently but also because outcome after AMR is distinctly better. HLAi and combined ABOi+HLAi transplantations appear to have the same outcome, suggesting there is no synergistic effect between anti‐A/B and anti‐HLA antibodies.

Clinical significance of isolated v lesions in paediatric renal transplant biopsies: muscular arteries required to refute the diagnosis of acute rejection

Intimal vascular lesions are considered features of acute T‐cell‐mediated rejection yet can occur in the absence of tubulointerstitial inflammation, termed isolated ‘v’ lesions. The clinical significance of these lesions is unclear. The diagnosis requires a biopsy with the presence of arteries. The frequency of adequate biopsies was analysed in 89 renal transplant biopsies from 57 paediatric renal allograft recipients, and the incidence of isolated endarteritis was determined. 60 (67%) biopsies contained an artery and of these, isolated ‘v’ lesions occurred in 6 (10%). 5 (83%) biopsies with isolated ‘v’ lesions were associated with positive DSA, suggesting that these lesions may represent acute antibody‐mediated rejection. Patients with vessel‐negative biopsies had an increased decline in eGFR (median −20.5, IQR −24.4 to 1.2 ml/min/1.73 m2 vs. −9.6, IQR −78.7 to −6.8 ml/min/1.73 m2; P = 0.01). Patients with vessel‐negative biopsies were more likely to have repeat biopsy for ongoing allograft dysfunction, (25.0% vs. 2.4%; P < 0.01). The data suggest that isolated ‘v’ lesions are more common than previously thought. A significant proportion of biopsies classified as ‘normal’ or ‘borderline change’ in the absence of a large vessel may represent undiagnosed acute rejection. This may result in suboptimal therapy with possible adverse effects on renal outcome.

How much donor human leukocyte antigen-specific antibody is too much for a renal transplant?

The communication in this issue from Gupta et al. (1) is timely and raises important practical questions which the Histocompatibility and Immunogenetics community needs to find coherent answers too. Most centers regard the presence of donor human leukocyte antigen (HLA)-specific antibody (DHSA) at the time of transplant as a contraindication to renal, pancreas, and heart transplantation. The authors have retrospectively analyzed 121 patients who received a renal transplant between 1999 and 2001. The recipients had negative complement-dependent lymphocytotoxic and flow cytometric crossmatches with their donor and received maintenance immunosuppression of Neoral, azothioprine, and prednisolone without induction therapy. Day-of-transplant sera were recently tested for HLA-specific antibody using the modern sensitive Luminex-based Labscreen (One Lambda Inc.) assay. Sixteen patients were found with detectable DHSA, and their allografts performed remarkably well when compared with the antibody-negative and antibody-positive but non-DHSA cohorts. There were no cases of hyperacute rejection, and no significant difference in delayed graft function, biopsy-proven acute rejection, and 1-year graft survival between the three groups. Multivariate analysis did indicate that the DHSA group had a worse longterm graft outcome. Registration of a UK patient for a deceased donor renal transplant requires that patients are screened for antibodies directed at HLA antigens and these antigens are listed as unacceptable. If the antigen is present on a deceased donor the recipient will not be offered the kidney. Patients are slightly discriminated against within the national sharing scheme if their antibodies are not fully characterized. The advent of methods for locus-specific HLA purification and recombinant technology has allowed single HLA alleles to be attached to microbeads suitable for flow cytometric analysis. Luminex-based kits are one of the most popular and sensitive of these methods. This has considerably increased the sensitivity and discriminatory powers of HLA-specific antibody detection. This, in turn, has led to an increasing list of unacceptable specificities being defined in sensitized patients. This article would suggest that many patients having their antibodies defined by these methods may not be receiving offers of renal transplantation that would provide them with good renal function for many years. The complement-dependent lymphocytotoxic crossmatching and antibody screening test has long been established as the gold standard methodology to which all emerging technologies are compared. The introduction of new and more sensitive techniques raises the question of whether we need more sensitivity? The authors present data from their center, which would indicate, in the short term at least, that by using these more sensitive techniques we may be disadvantaging our patients by refusing them potentially successful transplants. An alternative view would be to suggest that this highlights the need to understand the context of the test, and instead of analyzing antibody specificities as positive or negative, we should in fact be interpreting our results and defining antibodies by clinical significance, in the context of a patient’s sensitization history and using epitope analysis. For example an antibody raised directly to an HLA specificity present on a previous graft will potentially be more clinically significant than a low-level antibody to a crossreactive epitope. Most centers use these single antigen beads in addition to other antibody identification methods to allow a picture of clinically relevant specificities to develop. These specificities alone should be registered as unacceptable in matching algorithms, while accepting that other specificities may be present at low levels and may give negative crossmatches. This comprehensive analysis allows the laboratory to give as much information as possible to clinicians on the relative risk of a proposed transplant. The data presented in this article add to the argument to remove current positive and negative reporting systems and replace them with risk reporting, categorizing results into low, medium, and high risk. Many centers are now removing DHSA to enable a successful renal transplant and the reported results are generally very good. This is giving some insights with regard to acceptable thresholds for the anti-donor crossmatch and indicates the importance of the process known as accommodation. It is becoming clear that a low level of antibody may promote an antiapoptotic response from the endothelium and be beneficial to long-term engraftment (2). Collation and analysis of the laboratory tests and results of transplantation both before 1 King’s College, London, United Kingdom. 2 Clinical Transplantation Laboratory, 3rd Floor Borough Wing, Guy’s and St. Thomas NHS Foundation Trust, London, United Kingdom. 3 Address correspondence to: Robert Vaughan, Ph.D., FRCPath, 3rd Floor Borough Wing, Guy’s Campus, Kings College London, UK SE1 9RT. E-mail: robert.vaughn@kcl.ac.uk Received 11 January 2008. Accepted 24 January 2008. Copyright

The UK National Registry of ABO and HLA Antibody Incompatible Renal Transplantation: Pretransplant Factors Associated With Outcome in 879 Transplants

Background ABO and HLA antibody incompatible (HLAi) renal transplants (AIT) now comprise around 10% of living donor kidney transplants. However, the relationship between pretransplant factors and medium-term outcomes are not fully understood, especially in relation to factors that may vary between centers. Methods The comprehensive national registry of AIT in the United Kingdom was investigated to describe the donor, recipient and transplant characteristics of AIT. Kaplan-Meier analysis was used to compare survival of AIT to all other compatible kidney transplants performed in the United Kingdom. Cox proportional hazards regression modeling was used to determine which pretransplant factors were associated with transplant survival in HLAi and ABOi separately. The primary outcome was transplant survival, taking account of death and graft failure. Results For 522 HLAi and 357 ABO incompatible (ABOi) transplants, 5-year transplant survival rates were 71% (95% confidence interval [CI], 66-75%) for HLAi and 83% (95% CI, 78-87%) for ABOi, compared with 88% (95% CI, 87-89%) for 7290 standard living donor transplants, and 78% (95% CI, 77-79%) for 15 322 standard deceased donor transplants (P < 0.0001). Increased chance of transplant loss in HLAi was associated with increasing number of donor specific HLA antibodies, center performing the transplant, antibody level at the time of transplant, and an interaction between donor age and dialysis status. In ABOi, transplant loss was associated with no use of IVIg, cytomegalovirus seronegative recipient, 000 HLA donor-recipient mismatch; and increasing recipient age. Conclusions Results of AIT were acceptable, certainly in the context of a choice between living donor AIT and an antibody compatible deceased donor transplant. Several factors were associated with increased chance of transplant loss, and these can lead to testable hypotheses for further improving therapy.

Assessing the Feasibility of Deceased Donor ABO-Incompatible Transplantation in Wait-Listed Transplant Recipients.: Abstract# A163

A163 Assessing the Feasibility of Deceased Donor ABO-Incompatible Transplantation in Wait-Listed Transplant Recipients. M. Manook,1 D. Veniard,1 N. Barnett,2 O. Shaw,1 T. Maggs,1 N. Mamode.1 1Renal Transplant, Guys & St Thomas’ NHS Trust, London, United Kingdom; 2Colchester Hospital, London, United Kingdom. Introduction: Outcomes for living donor ABO-Incompatible are widely accepted as being favourable. In our centre, a tailored approach to desensitisation for ABOi is used, based on baseline ABO antibody titres.1 For patients with titres < 1:8, no additional treatment is given compared to ABO-compatible transplants. This offers the potential of deceased donor ABOi (DD ABOi) transplantation. This study was to determine the feasibility of DD ABOi in a single centre Methods: Prospective cohort study of ABO antibody titres & calculated reaction frequency (CRF) in active & suspended patients on the adult renal transplant waiting list in a single centre. Total immunoglobulin (Ig) Anti-A & Anti-B titres were measured by the Indirect Antiglobulin Test (IAT) using Biorad gel cards (Coombs anti-IgG) on untreated plasma capturing initial IgM binding & subsequent IgG. Results: Of the 124 patients tested, 3 (2.4%) were excluded from analysis due to the presence of atypical antibodies. 60% (n=72) were male. Blood group distribution was A 29.2% (n = 35); B 11.7% (n= 14); O 56.7% (n=68); AB 2.5% (n=3) Black ethnicity was the most common (50%), White (35.8%), Asian (7.5%). Of the patients screened, 3 had ‘neat’ anti-A or Anti-B titres. 25% (n=30) had either an anti-A or anti-B titre of 1:8 or less – ‘low titre’ (of these 10% were on immunosuppressive medication). Haemagglutinin titres varied with blood group: Grp A 21 ‘low titre’ vs14 high titre; Grp B 3 ‘low’ vs11 high, Grp O 3 ‘low’ vs 65 high, p = <0.02 .For Group O, Anti-A titres were higher than antiB (median anti-A titre 1:256, median anti-B titres 1:128), 26.5% of Group O’s had a greater than expected dilution difference (>2) between anti-A & Anti-B. Mean Calculated Reaction Frequency (CRF – a measure of anti-HLA antibody) was 43.5% (SD 43.2) Comparing a high CRF (>80%) to low there was no signifi cant difference in mean anti-A (p = 0.6) or anti-B titre (p=0.3). There was no correlation between anti-A or anti-B & CRF. Discussion: Preliminary results suggest that 25% of patients on the deceased donor waiting list would be suitable for DD ABOi transplantation without any additional treatment. Patients who are highly sensitised to HLA-antibody do not have high ABO antibody titres. Further work to follow up the cohort is planned DISCLOSURES: Manook, M.: Grant/Research Support, Glycorex. Mamode, N.: Grant/Research Support, Alexion, Astellas. Abstract# A164 Does Recipient Race Affect Alloantibody Presentation and Graft Outcome? P. Kimball, A. Sharma, F. McDougan, A. King. Transplant Surgery, Virginia Commonwealth Univ. Health Systems, Richmond. Purpose. African Americans (AA) are more likely to be sensitized against HLA antigens and have poorer renal transplant (RT) outcomes than Caucasian Americans (CA). We speculated that alloantibody presentation might differ between AA and CA and contribute to different outcomes. Methods. Among 253 RT recipients, 71 were targeted for preemptive desensitization due to PRA >50%, FCXM > 100 MCS and DGF. Alloantibody content was identifi ed by fl ow crossmatch (FC) and DSA using single antigen bead luminex. Postransplant antibody was tested quarterly. Results. More AA than CA needed desensitization (31% vs. 22%, p<0.05). Preoperatively, more AA than CA were FC+DSA+ (70 vs. 43%, p<0.05). CA tended to be FC+ only (57% vs. 30%, p<0.05) which is considered non-HLA. Multiple DSA were prevalent for AA than CA(78% vs. 28%, p<0.05). DSA against both Class I and II was prevalent among AA than CA (40% vs. 12%, p<0.05). DSA strength (MFI) against Class I was equivalent (p=ns) between AA and CA (6606 ±4472 vs. 8323 ±3471). MFI against Class II increased 2-fold among AA (10,247 ±5015, p=0.01) but not CA (8707 ±7045. p=ns). FC strength (MCS) against Class I was higher for AA than CA (114 ±90 vs. 50 ±72 MCS, p=0.01) but equivalent against Class II (117 ±70 vs. 137 ±77 MCS, p=ns). After RT, alloantibody clearance was equivalent between AA and CA for FC+DSA+ (31% vs. 37%, p=ns) and FC+ (42% vs. 33%, p=ns). Among patients with alloantibody elimination, graft outcomes were equivalent between AA and CA with 100% 2-yr graft survival. In contrast, AA with antibody persistence had more rejections (33% vs. 0%, p<0.05) and poorer 2 yr graft survival (60% vs. 100%, p<0.05) than CA. Similar results were seen with FC+ only. Conclusions. AA and CA variation in antibody content may impact outcome. AA had anti-HLA DSA whereas CA had non-HLA antibody. AA had multiple DSAs, higher DSA levels particularly against Class II. A164 Does Recipient Race Affect Alloantibody Presentation and Graft Outcome? P. Kimball, A. Sharma, F. McDougan, A. King. Transplant Surgery, Virginia Commonwealth Univ. Health Systems, Richmond. Purpose. African Americans (AA) are more likely to be sensitized against HLA antigens and have poorer renal transplant (RT) outcomes than Caucasian Americans (CA). We speculated that alloantibody presentation might differ between AA and CA and contribute to different outcomes. Methods. Among 253 RT recipients, 71 were targeted for preemptive desensitization due to PRA >50%, FCXM > 100 MCS and DGF. Alloantibody content was identifi ed by fl ow crossmatch (FC) and DSA using single antigen bead luminex. Postransplant antibody was tested quarterly. Results. More AA than CA needed desensitization (31% vs. 22%, p<0.05). Preoperatively, more AA than CA were FC+DSA+ (70 vs. 43%, p<0.05). CA tended to be FC+ only (57% vs. 30%, p<0.05) which is considered non-HLA. Multiple DSA were prevalent for AA than CA(78% vs. 28%, p<0.05). DSA against both Class I and II was prevalent among AA than CA (40% vs. 12%, p<0.05). DSA strength (MFI) against Class I was equivalent (p=ns) between AA and CA (6606 ±4472 vs. 8323 ±3471). MFI against Class II increased 2-fold among AA (10,247 ±5015, p=0.01) but not CA (8707 ±7045. p=ns). FC strength (MCS) against Class I was higher for AA than CA (114 ±90 vs. 50 ±72 MCS, p=0.01) but equivalent against Class II (117 ±70 vs. 137 ±77 MCS, p=ns). After RT, alloantibody clearance was equivalent between AA and CA for FC+DSA+ (31% vs. 37%, p=ns) and FC+ (42% vs. 33%, p=ns). Among patients with alloantibody elimination, graft outcomes were equivalent between AA and CA with 100% 2-yr graft survival. In contrast, AA with antibody persistence had more rejections (33% vs. 0%, p<0.05) and poorer 2 yr graft survival (60% vs. 100%, p<0.05) than CA. Similar results were seen with FC+ only. Conclusions. AA and CA variation in antibody content may impact outcome. AA had anti-HLA DSA whereas CA had non-HLA antibody. AA had multiple DSAs, higher DSA levels particularly against Class II. Abstract# A165 Anti-ABO Specific Assay Variability Affects Antibody Removal in ABO Incompatible Kidney Transplantation (ABOiKTx) UK Multicentre Study. A. Bentall,1 M. Kaur,1 N. Mamode,3 D. Briggs,2 N. Kessaris,3 S. Ball.1 1Department of Nephrology and Transplantation, University Hospitals Birmingham, Birmingham, United Kingdom; 2Department of Histocompatibility, NHSBT, Birmingham, United Kingdom; 3Department of Transplantation, Guys and St Thomas Hospital, London, United Kingdom. INTRODUCTION: ABOiKTx outcomes are reported better outcomes in single centres than in registry data. Intracentre and intercentre variability in ABO blood group antibody titres has been reported without clinical correlate. In a multi-centre observational study, we report the clinical outcomes and anti-ABO titre variations between centres and the impact on clinical practice. METHODS: 100 patients recruited received an ABOiKTx and data and samples were collected prospectively and analysed by blood group and extracorporeal antibody treatment (EART). Samples were analysed locally and central samples were retrospectively analysed. A single technician undertook analysis of all samples, initially demonstrating excellent reproducibility within same red cell batch; using different batches; freeze thaw repeats and on different days. RESULTS: Patient and graft survival at 1 year were 99% and 94% respectively. 70 patients were blood group ‘O’. 36 were pre-emptive transplants and 86 were 1st transplants. 80 patients had rituximab for induction. 55 patients had immunoadsorption(IA) and 31 had plasma exchange (PEx). There was no difference in clinical outcomes between IA and PEx in graft survival (Figure 1A). 29 patients experience acute rejection with 4 with antibody-mediated rejection with more rejection in blood group B recipients(Figure1B). CMV and BK nephropathy occurred in 3 and 5 patients respectively. ABO titres were higher in local assays in PEx cohort, and received more EART, however when analysed centrally, there was no signifi cant difference in ABO titres between IA and PEx. A165 Anti-ABO Specific Assay Variability Affects Antibody Removal in ABO Incompatible Kidney Transplantation (ABOiKTx) UK Multicentre Study. A. Bentall,1 M. Kaur,1 N. Mamode,3 D. Briggs,2 N. Kessaris,3 S. Ball.1 1Department of Nephrology and Transplantation, University Hospitals Birmingham, Birmingham, United Kingdom; 2Department of Histocompatibility, NHSBT, Birmingham, United Kingdom; 3Department of Transplantation, Guys and St Thomas Hospital, London, United Kingdom. INTRODUCTION: ABOiKTx outcomes are reported better outcomes in single centres than in registry data. Intracentre and intercentre variability in ABO blood group antibody titres has been reported without clinical correlate. In a multi-centre observational study, we report the clinical outcomes and anti-ABO titre variations between centres and the impact on clinical practice. METHODS: 100 patients recruited received an ABOiKTx and data and samples were collected prospectively and

A new approach to HLA typing designed for solid organ transplantation: Epityping and its application to the HLA-A locus

HLA‐specific antibodies bind discrete clusters of amino acids called epitopes, but serological assignment of antibody specificities makes no reference to this. As HLA typing for solid organ transplantation is provided at only medium (serologically equivalent) resolution, this means that recipient HLA antibodies to donor HLA epitopes may not be identified. We have designed a novel and rapid HLA‐A epitope typing method (epityping) using a two‐stage PCR‐SSP‐based method to detect the HLA‐A locus epitopes described by El Awar et al. 2007, Transplantation, 84, 532. The initial PCR step utilizes HLA‐A locus‐specific primers; the product is cleaned using the QIAquick Spin Purification procedure. The purified product is tested using our in‐house epitope‐specific primer panel, the results being visualized using gel electrophoresis. Twenty two UCLA DNA Exchange samples were epityped, blinded to the HLA type. Of the 75 primer pairs, the mean correlation coefficient was 0.95 with each sample giving 67 or more correct primer results. In all cases, it was possible to derive the first field classic HLA type from the epityping results. These results indicate that a method for identification of HLA epitopes which is comparable in time, cost and technical expertise to current HLA typing methods is achievable. Redesigning HLA typing to correlate with what the antibody binds should minimize inappropriate organ allocation. We suggest that epityping provides a more effective method than standard HLA typing for solid organ transplantation.

P19-20. Allogeneic stimulation of the anti-viral APOBEC3G in human CD4+ T cells and prevention of SHIV infectivity in macaques immunized with HLA antigens

Address: 1Mucosal Immunology Unit, Kings College London, London, UK, 2Immunodex, Copenhagen, Denmark, 3National Institute of Health, Bethesda, MD, USA, 4Lionex Diagnostics & Therapeutics, Braunschweig, Germany, 5Academic Medical Center, Amsterdam, Netherlands, 6Chinese Centre for Disease Control and Prevention, Beijing, PR China and 7Swedish Institute for Infectious Disease Control, Stockholm, Sweden * Corresponding author