Comparison of kidney transplant outcomes in HLA compatible and incompatible transplantation: A national cohort study.

BACKGROUND: Reports of HLA incompatible (HLAi) kidney transplant outcomes are inconclusive, especially in the context of lower level Donor Specific Antibodies (DSA). METHODS: Multi-centre national cohort study of HLAi kidney transplant recipients matched in 1:2 ratio with HLA compatible (HLAc) kidney transplant recipients. HLAi defined as DSA identified by Luminex. Antibody mediated rejection (AMR) and transplant-survival were analysed using Kaplan-Meier plots. Propensity score (PS) matching was used to compare recipient and transplant survival between groups. RESULTS: We included 61 HLAi and 122 HLAc recipients; mean age 46 years; 60% female. MFIT0 : 3327 (IQR 1352-6458), 23 (38%) were Flow cytometry crossmatch positive (FC-XMPOS ). DSAPOS /FC-XMPOS transplantation carried an increased risk of AMR at 1 year (52%) compared to DSAPOS /FC-XMNEG (27%) and HLAc (0%). Unadjusted death censored graft loss at 3 years was 13% (HLAi) and 8% (HLAc). Three-year patient survival was 95% in HLAc, 84% in DSAPOS /FC-XMNEG and 69% in DSAPOS /FC-XMPOS recipients; 58% of HLAi deaths were infection-related. HLA incompatibility was associated with a decreased 3-year survival in our PS-matched cohort. CONCLUSION: In kidney transplantation, DSA and positive FC-XM carries an increased risk of AMR. Despite inferior transplant and survival outcomes compared to HLAc transplantation, it remains a realistic option for highly sensitized patients facing prolonged waiting times and reduced survival on dialysis.

BSHI guideline: HLA matching and donor selection for haematopoietic progenitor cell transplantation.

A review of the British Society for Histocompatibility and Immunogenetics (BSHI) Guideline 'HLA matching and donor selection for haematopoietic progenitor cell transplantation' published in 2016 was undertaken by a BSHI appointed writing committee. Literature searches were performed and the data extracted were presented as recommendations according to the GRADE nomenclature.

HLA Immunogenotype Determines Persistent Human Papillomavirus Virus Infection in HIV-Infected Patients Receiving Antiretroviral Treatment.

A proportion of human immunodeficiency virus (HIV)-infected patients develop persistent, stigmatizing human papillomavirus (HPV)-related cutaneous and genital warts and anogenital (pre)cancer. This is the first study to investigate immunogenetic variations that might account for HPV susceptibility and the largest to date to categorize the HPV types associated with cutaneous warts in HIV-positive patients. The HLA class I and II allele distribution was analyzed in 49 antiretroviral (ART)-treated HIV-positive patients with persistent warts, 42 noninfected controls, and 46 HIV-positive controls. The allele HLA-B*44 was more frequently identified in HIV-positive patients with warts (P = .004); a susceptible haplotype (HLA-B*44, HLA-C*05; P = .001) and protective genes (HLA-DQB1*06; P = .03) may also contribute. Cutaneous wart biopsy specimens from HIV-positive patients harbored common wart types HPV27/57, the unusual wart type HPV7, and an excess of Betapapillomavirus types (P = .002), compared with wart specimens from noninfected controls. These findings suggest that HLA testing might assist in stratifying those patients in whom vaccination should be recommended.

Modeling HLA associations with EBV-positive and -negative Hodgkin lymphoma suggests distinct mechanisms in disease pathogenesis.

HLA genotyping and genome wide association studies provide strong evidence for associations between Human Leukocyte Antigen (HLA) alleles and classical Hodgkin lymphoma (cHL). Analysis of these associations is complicated by the extensive linkage disequilibrium within the major histocompatibility region and recent data suggesting that associations with EBV-positive and EBV-negative cHL are largely distinct. To distinguish independent and therefore potentially causal associations from associations confounded by linkage disequilibrium, we applied a variable selection regression modeling procedure to directly typed HLA class I and II genes and selected SNPs from EBV-stratified patient subgroups. In final models, HLA-A*01:01 and B*37:01 were associated with an increased risk of EBV-positive cHL whereas DRB1*15:01 and DPB1*01:01 were associated with decreased risk. Effects were independent of a prior history of infectious mononucleosis. For EBV-negative cHL the class II SNP rs6903608 remained the strongest predictor of disease risk after adjusting for the effects of common HLA alleles. Associations with "all cHL" and differences by case EBV status reflected the subgroup analysis. In conclusion, this study extends previous findings by identifying novel HLA associations with EBV-stratified subgroups of cHL, highlighting those alleles likely to be biologically relevant and strengthening evidence implicating genetic variation associated with the SNP rs6903608.

Synergism of tapasin and human leukocyte antigens in resolving hepatitis C virus infection.

UNLABELLED: CD8+ T-cell responses to hepatitis C virus (HCV) are important in generating a successful immune response and spontaneously clearing infection. Human leukocyte antigen (HLA) class I presents viral peptides to CD8+ T cells to permit detection of infected cells, and tapasin is an important component of the peptide loading complex for HLA class I. We sought to determine if tapasin polymorphisms affected the outcome of HCV infection. Patients with resolved or chronic HCV infection were genotyped for the known G/C coding polymorphism in exon 4 of the tapasin gene. In a European, but not a US, Caucasian population, the tapasin G allele was significantly associated with the outcome of HCV infection, being found in 82.5% of resolvers versus 71.3% of persistently infected individuals (P = 0.02, odds ratio [OR] = 1.90 95% confidence interval [CI] = 1.11-3.23). This was more marked at the HLA-B locus at which heterozygosity of both tapasin and HLA-B was protective (P < 0.03). Individuals with an HLA-B allele with an aspartate at residue 114 and the tapasin G allele were more likely to spontaneously resolve HCV infection (P < 0.00003, OR = 3.2 95% CI = 1.6-6.6). Additionally, individuals with chronic HCV and the combination of an HLA-B allele with an aspartate at residue 114 and the tapasin G allele also had stronger CD8+ T-cell responses (P = 0.02, OR = 2.58, 95% CI-1.05-6.5). CONCLUSION: Tapasin alleles contribute to the outcome of HCV infection by synergizing with polymorphisms at HLA-B in a population-specific manner. This polymorphism may be relevant for peptide vaccination strategies against HCV infection.

HLA-A alleles and infectious mononucleosis suggest a critical role for cytotoxic T-cell response in EBV-related Hodgkin lymphoma.

A proportion of classical Hodgkin lymphoma (HL) is believed to be causally related to infection with the ubiquitous lymphotropic EBV. The determining factors for development of EBV-related HL remain poorly understood, but likely involve immunological control of the viral infection. Accordingly, markers of the HLA class I region have been associated with risk of EBV-related HL. To study the host genetic component of EBV-related HL further, we investigated the lymphoma's association with HLA-A*01 and HLA-A*02 simultaneously in the setting of infectious mononucleosis (IM), a risk factor for EBV-related HL, in a case-series analysis including 278 EBV-related and 656 EBV-unrelated cases of HL. By logistic regression, HLA-A*01 alleles [odds ratio (OR) per allele, 2.15; 95% CI, 1.60-2.88] were associated with increased and HLA-A*02 alleles (OR per allele, 0.70; 95% CI, 0.51-0.97) with decreased risk of EBV-related HL. These allele-specific associations corresponded to nearly 10-fold variation in risk of EBV-related HL between HLA-A*01 and HLA-A*02 homozygotes. History of IM was also associated with risk of EBV-related HL (OR, 3.40; 95% CI, 1.74-6.66). The association between history of IM and EBV-related HL was not seen in the presence of HLA-A*02 because this allele appeared to neutralize the effect of IM on EBV-related HL risk. Our findings suggest that HLA class I-restricted EBV-specific cytotoxic T-cell responses and events in the early immune response to EBV infection in IM play critical roles in the pathogenesis of EBV-related HL.

Kidney transplant outcomes in patients with antibodies to human neutrophil antigen 3a.

BACKGROUND: Antibody mediated rejection (ABMR) of kidney transplants has been shown to occur in the absence of a known donor specific antibody to human leucocyte antigen (HLA). Antibodies to the human neutrophil antigen (HNA) system have been detected in kidney transplant recipients and linked to ABMR in the absence of an HLA donor specific antibody (DSA), but there remains limited literature regarding this. METHODS: Case series analysis was carried out examining three cases of HNA-3a antibody positive flow cytometry cross match (FC-XM) from two transplant centres in Scotland. RESULTS: All patients included were female and had been sensitised as a result of pregnancy. One live donor recipient with HNA-3a antibodies identified prior to transplant received ATG induction and has had a good outcome. The remaining two patients received deceased donor transplants. HNA-3a antibodies were indicated following a retrospective flow cytometry crossmatch. Both patients received Basiliximab induction and both have experienced ABMR requiring supplementary immunosuppression. CONCLUSIONS: The predicted rate of HNA-3a antibodies amongst patients awaiting kidney transplant in the UK is <1%. However, with increasing evidence to support a role for HNA-3a antibodies in the development of ABMR there may be value in screening at risk groups to allow for augmented immunosuppression to be considered at the time of kidney transplant.

Cytomegalovirus-specific CD8+ T cells targeting different peptide/HLA combinations demonstrate varying T-cell receptor diversity.

Cytomegalovirus (CMV) infection and reactivation pose a serious threat for patients after haematopoietic stem cell transplantation. We have previously shown that CD8(+) T cells targeting different CMV epitopes correlate with protection at different threshold frequencies in those patients. To investigate if this may relate to a different quality of these cells here we analyse the T-cell receptor diversity of pp50 (245-253)/HLA-A*0101 specific CD8(+) T cells with that of CD8(+) T cells targeting various pp65 peptides. The results from this pilot study show differences in the breadth of the T-cell receptor usage of the different cell populations. We observe for the first time that the T-cell receptor Vß CDR3 spectratypes used by CMV pp50 (245-253)/HLA-A*0101-specific CD8(+) T cells can reach higher numbers than those used by CD8(+) T cells targeting various pp65 peptides in our patient cohort. This merits further investigation into the effectiveness of the different CMV-specific T cells and their impact on immunosenescence, which is important to eventually define the most useful source of adoptive therapy and monitoring protocols for cytomegalovirus-specific immune responses.

Roles for HLA and KIR polymorphisms in natural killer cell repertoire selection and modulation of effector function.

Interactions between killer cell immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) class I ligands regulate the development and response of human natural killer (NK) cells. Natural selection drove an allele-level group A KIR haplotype and the HLA-C1 ligand to unusually high frequency in the Japanese, who provide a particularly informative population for investigating the mechanisms by which KIR and HLA polymorphism influence NK cell repertoire and function. HLA class I ligands increase the frequencies of NK cells expressing cognate KIR, an effect modified by gene dose, KIR polymorphism, and the presence of other cognate ligand-receptor pairs. The five common Japanese KIR3DLI allotypes have distinguishable inhibitory capacity, frequency of cellular expression, and level of cell surface expression as measured by antibody binding. Although KIR haplotypes encoding 3DL1*001 or 3DL1*005, the strongest inhibitors, have no activating KIR, the dominant haplotype encodes a moderate inhibitor, 3DL1*01502, plus functional forms of the activating receptors 2DL4 and 2DS4. In the population, certain combinations of KIR and HLA class I ligand are overrepresented or underrepresented in women, but not men, and thus influence female fitness and survival. These findings show how KIR-HLA interactions shape the genetic and phenotypic KIR repertoires for both individual humans and the population.

A polymorphism in IL28B distinguishes exposed, uninfected individuals from spontaneous resolvers of HCV infection.

BACKGROUND & AIMS: Polymorphisms in the interleukin-28B (IL28B) gene are associated with outcomes from infection with hepatitis C virus (HCV). However, the role of these polymorphisms in protecting injection drug users who are at high risk for HCV infection but do not have detectable antibodies against HCV or HCV RNA (exposed uninfected) has not been demonstrated. We investigated whether these individuals have the IL28B genotype rs12979860-CC, which protects some individuals against HCV infection. METHODS: Seventy-four exposed uninfected individuals, 89 spontaneous resolvers, and 234 chronically infected individuals were genotyped to determine single nucleotide polymorphisms at IL28B.rs12979860. RESULTS: Exposed, uninfected individuals had a significantly lower frequency of the protective genotype (rs12979860-CC) than anti-HCV-positive spontaneous resolvers (41.9% vs 69.7%, respectively; P=.0005; odds ratio [OR], 0.31; 95% confidence interval [CI]: 0.16-0.60) but a similar frequency to patients who were chronically infected (41.9% vs 43.6%, respectively; P=ns). However, exposed, uninfected individuals had a significantly higher frequency of homozygosity for killer cell immunoglobulin-like receptor 2DL3:group 1 HLA-C (KIR2DL3:HLA-C1) than those with chronic infection (31.1% vs 13.3%, respectively; P=.0008; OR, 2.95; 95% CI: 1.59-5.49). For patients who spontaneously resolved infection, IL28B and KIR:HLA protected, independently, against chronic HCV infection, based on logistic regression and synergy analyses (synergy factor, 1.3; 95% CI: 0.37-4.75; P synergy=.6). CONCLUSIONS: IL28B and KIR2DL3:HLA-C1 are independently associated with spontaneous resolution of viremia following HCV exposure. Resistance to HCV infection in exposed uninfected cases is associated with homozygosity for KIR2DL3:HLA-C1 but not the single nucleotide polymorphism IL28B.rs12979860. Uninfected individuals are therefore a distinct population from patients who spontaneously resolve HCV infection. Distinct, nonsynergistic innate immune mechanisms can determine outcomes of HCV exposure.

Consistent beneficial effects of killer cell immunoglobulin-like receptor 2DL3 and group 1 human leukocyte antigen-C following exposure to hepatitis C virus.

UNLABELLED: Natural killer cells are a key component in the immune control of viral infections. Their functions are controlled by inhibitory receptors for major histocompatability complex (MHC) class I, including the killer cell immunoglobulin-like receptors (KIR). KIR2DL3 in combination with its cognate human leukocyte antigen (HLA)-C ligand has been shown to be associated with spontaneous resolution of viremia following hepatitis C virus (HCV) infection. In order to determine if this gene combination is advantageous across all potential outcomes following HCV exposure, we studied individuals with apparent resistance to HCV infection who remain seronegative and aviremic despite long-term injection drug use and also individuals chronically infected with HCV who successfully clear HCV with treatment. Homozygosity for KIR2DL3 in combination with group 1 HLA-C allotypes was more frequent in exposed seronegative aviremic individuals as compared to those with chronic HCV (25.0% versus 9.7%, P = 0.003, odds ratio [OR] = 3.1, 95% confidence interval [CI] = 1.3-7.1) in a model similar to that found for those spontaneously resolving HCV. In individuals undergoing treatment for HCV, those with KIR2DL3 and group 1 HLA-C were more likely to make a sustained virological response (SVR) (P = 0.013, OR = 2.3, 95% CI = 1.1-4.5). KIR and HLA-C protection in both treatment response and spontaneously resolving HCV was validated at the allelic level, in which KIR2DL3-HLA-Cw*03 was associated with SVR (P = 0.004, OR = 3.4, 95% CI = 1.5-8.7) and KIR2DL3/KIR2DL3-HLA-Cw*03 was associated with spontaneous resolution of HCV infection (P = 0.01, OR = 2.3, 95% CI = 1.2-4.4). CONCLUSION: KIR and HLA-C genes are consistently beneficial determinants in the outcome of HCV infection. This advantage extends to the allelic level for both gene families.

MHC class I-specific inhibitory receptors and their ligands structure diverse human NK-cell repertoires toward a balance of missing self-response.

Variegated expression of 6 inhibitory HLA class I-specific receptors on primary NK cells was studied using high-dimension flow cytometry in 58 humans to understand the structure and function of NK-cell repertoires. Sixty-four subsets expressing all possible receptor com-binations were present in each repertoire, and the frequency of receptor-null cells varied among the donors. Enhancement in missing-self response between NK subsets varied substantially where subset responses were defined by donor KIR/HLA allotypes, reflecting the differences in interaction between inhibitory receptors and their ligands. This contrasted to the enhancement conferred by NKG2A, which was constant and of intermediate strength. We infer a mechanism that modulates frequencies of the NK subsets displaying diverse levels of missing-self response, a system that reduces the presence of KIR-expressing subsets that display either too strong or too weak a response and effectively replaces them with NKG2A-expressing cells in the repertoire. Through this high-resolution analysis of inhibitory receptor expression, 5 types of NK-cell repertoire were defined by their content of NKG2A(+)/NKG2A(-) cells, frequency of receptor-null cells, and degree of KIR receptor coexpression. The analyses provide new perspective on how personalized human NK-cell repertoires are structured.

Adenovirus E3/19K promotes evasion of NK cell recognition by intracellular sequestration of the NKG2D ligands major histocompatibility complex class I chain-related proteins A and B.

The adenovirus (Ad) early transcription unit 3 (E3) encodes multiple immunosubversive functions that are presumed to facilitate the establishment and persistence of infection. Indeed, the capacity of E3/19K to inhibit transport of HLA class I (HLA-I) to the cell surface, thereby preventing peptide presentation to CD8(+) T cells, has long been recognized as a paradigm for viral immune evasion. However, HLA-I downregulation has the potential to render Ad-infected cells vulnerable to natural killer (NK) cell recognition. Furthermore, expression of the immediate-early Ad gene E1A is associated with efficient induction of ligands for the key NK cell-activating receptor NKG2D. Here we show that while infection with wild-type Ad enhances synthesis of the NKG2D ligands, major histocompatibility complex class I chain-related proteins A and B (MICA and MICB), their expression on the cell surface is actively suppressed. Both MICA and MICB are retained within the endoplasmic reticulum as immature endoglycosidase H-sensitive forms. By analyzing a range of cell lines and viruses carrying mutated versions of the E3 gene region, E3/19K was identified as the gene responsible for this activity. The structural requirements within E3/19K necessary to sequester MICA/B and HLA-I are similar. In functional assays, deletion of E3/19K rendered Ad-infected cells more sensitive to NK cell recognition. We report the first NK evasion function in the Adenoviridae and describe a novel function for E3/19K. Thus, E3/19K has a dual function: inhibition of T-cell recognition and NK cell activation.

Cord blood stem cells for hematopoietic stem cell transplantation in the UK: how big should the bank be?

BACKGROUND: A stored cord blood donation may be a valuable source of hemopoietic stem cells for allogeneic transplantation when a matched sibling donor is not available. We carried out a study to define the optimal size of a national cord blood bank for the UK. DESIGN AND METHODS: We calculated the actual numbers of possible donors and the chance of finding at least one donor for 2,000 unselected and for 722 non-North Western European patients for whom searches had been initiated as a function of three levels of HLA matching (4, 5 and 6 out of 6 alleles by HLA-A, -B low and -DRB1 high resolution HLA typing) according to various donor bank sizes. RESULTS: With a bank size of 50,000, 80% of patients will have at least one donor unit available at the 5 out of 6 HLA allele match level (median 9 donors per patient), and 98% will have at least one donor at the 4 out of 6 allele match level (median 261). Doubling the size of the bank yields at least one donor for only an additional 6% of patients at the 5 of 6 allele match level. Moreover, for non-North Western European patients a 50,000 unit bank provides a donor for 50% at the 5 allele match level, and for 96% at the 4 allele match level. CONCLUSIONS: A bank containing 50,000 units is optimal for the UK and larger banks would only marginally increase the chance of finding suitable units.

HLA antibodies in haematopoietic stem cell transplantation.

The negative impact of donor specific HLA alloantibodies in solid organ transplantation is well known and understood within the histocompatibility and immunogenetics community. However the influence of donor-specific antibodies in the outcome of haematopoietic stem cell transplantation is less well regarded. As donor choices have evolved from HLA matched siblings and extremely well matched unrelated donors to mismatched cord blood and haplo-identical-related donors, we are now identifying more patients with antibodies reactive against their donor mismatches. The clinical significance of the antibodies that can be detected has not yet been fully elucidated.

The omission of the "wet" pre-transplant crossmatch in renal transplant centres in Scotland.

The methods used for assessment of immunological risk for a patient receiving a kidney from a deceased donor have undergone significant change in the last few years. Many centres now proceed to transplant without any additional laboratory-based HLA testing for patients who are well defined as HLA antibody negative. Using rapid HLA antibody tests at the time of donor offer, such as Luminex, it is also possible to omit wet crossmatches in many sensitised patients. This virtual crossmatch (vXM) approach provides benefits in reducing cold ischaemia time (CIT), but also carries risks such as missing clinically relevant non-HLA reactivity or allelic HLA antibody reactivity. A number of factors need to be in place in a laboratory to enable a vXM policy to be extended to both sensitised and non-sensitised patients including access to complete donor HLA typing, ability to undertake Luminex-based HLA antibody testing out of working hours, and access to senior H&I Scientist expertise to assess and interpret results. Other approaches, such as using peripheral blood lymphocytes for crossmatching, may also enable a reduction in CIT and transplant units need to assess the risks of extending vXM processes for their patients against potential benefits.

An overview of HLA typing for hematopoietic stem cell transplantation.

Selection of a related or unrelated haematopoietic stem cell donor for a patient requires accurate matching of human leukocyte antigen (HLA) genes in order to maximise the beneficial effects of the transplant. There are a number of different approaches that can be made in order to achieve HLA type depending on the number of samples being processed, the level of resolution to be achieved, and the cost of providing the various tests. Each method has its advantages and disadvantages and in most laboratories, a combination of methods may be used.

Identification of Molecular Markers of Delayed Graft Function Based on the Regulation of Biological Ageing.

INTRODUCTION: Delayed graft function is a prevalent clinical problem in renal transplantation for which there is no objective system to predict occurrence in advance. It can result in a significant increase in the necessity for hospitalisation post-transplant and is a significant risk factor for other post-transplant complications. METHODOLOGY: The importance of microRNAs (miRNAs), a specific subclass of small RNA, have been clearly demonstrated to influence many pathways in health and disease. To investigate the influence of miRNAs on renal allograft performance post-transplant, the expression of a panel of miRNAs in pre-transplant renal biopsies was measured using qPCR. Expression was then related to clinical parameters and outcomes in two independent renal transplant cohorts. RESULTS: Here we demonstrate, in two independent cohorts of pre-implantation human renal allograft biopsies, that a novel pre-transplant renal performance scoring system (GRPSS), can determine the occurrence of DGF with a high sensitivity (>90%) and specificity (>60%) for donor allografts pre-transplant, using just three senescence associated microRNAs combined with donor age and type of organ donation. CONCLUSION: These results demonstrate a relationship between pre-transplant microRNA expression levels, cellular biological ageing pathways and clinical outcomes for renal transplantation. They provide for a simple, rapid quantitative molecular pre-transplant assay to determine post-transplant allograft function and scope for future intervention. Furthermore, these results demonstrate the involvement of senescence pathways in ischaemic injury during the organ transplantation process and an indication of accelerated bio-ageing as a consequence of both warm and cold ischaemia.

Unrelated umbilical cord blood transplants in adults: Early recovery of neutrophils by supportive co-transplantation of a low number of highly purified peripheral blood CD34+ cells from an HLA-haploidentical donor.

UNLABELLED: OBJECTIVE, METHODS, AND RESULTS: To reduce the period of posttransplant neutropenia and related early morbidity and mortality of cord blood (CB) transplants, we assessed the feasibility of co-infusion of a low number of highly purified peripheral blood CD34+ cells from a related haploidentical donor with a CB graft. Between March 1999 and May 2002, 11 patients with high-risk hematologic malignancies were transplanted using this strategy. The seven patients who received a haploidentical peripheral blood graft and a CB graft from a sibling (6) or the father (1) had prompt recovery (9-17 days, median 10) of the absolute neutrophil count (ANC) to greater than 0.5 x 10(9)/L. Analysis of DNA polymorphisms showed initial predominance of the haploidentical genotype both in granulocytes and in mononuclear cells, and subsequent progressive replacement by cells of CB genotype until final complete CB chimerism was achieved by patients who survived for sufficient periods of time. The four patients who received maternal haploidentical cells had no significant contribution of these to blood leukocytes, although complete CB chimerism was achieved by three of them and two reached engraftment of the CB on days +20 and +36. Morbidity due to early bacterial or fungal infections was remarkably low in patients with prompt ANC recovery. CONCLUSION: Our data show that co-infusion of a CB unit and a low number of haploidentical CD34+ cells may result in a shortened period of posttransplant neutropenia. This is likely the result of prompt and transient engraftment of the haploidentical hematopoietic stem cells that may provide the patient antimicrobial protection until the later engraftment of the CB hematopoietic stem cells.