B-cell depletion abrogates immune mediated cytopenia and rejection of cord blood transplantation in Hurler syndrome.

Umbilical cord blood is the preferred donor cell source for children with Inherited Metabolic disorders undergoing Hematopoietic Cell Transplant (HCT), and its use has been associated with improved "engrafted survival" and higher donor chimerism compared to other cell sources. However, as in other pediatric cord blood transplants for non-malignant disease, immune-mediated cytopenia and primary graft failure limit its use, and the latter remains the commonest cause of death following cord blood transplant for non-malignant disease. We have previously shown an association between immune-mediated cytopenia and graft failure in inherited metabolic diseases suggesting that both immune-mediated cytopenia and graft failure could be mediated by antibodies from the residual recipient B cells. Since rituximab is effective in depletion of B cells and management of refractory immune-mediated cytopenia following HCT, we have added rituximab to the conditioning regimen. We studied 57 patients in 2 centers who received myeloablative conditioning for cord blood transplant in Hurler syndrome, and report a significant improvement in event-free survival with reduced incidence of graft failure and without any evidence of immune-mediated cytopenia in those patients that had received rituximab.

Changes in the incidence, patterns and outcomes of graft failure following hematopoietic stem cell transplantation for Hurler syndrome.

Hematopoietic stem cell transplantation (HSCT) is the standard of care in children with Hurler syndrome (HS) as it is the only therapy that can arrest disease progression. We examined the incidence, patterns and outcomes of graft failure in all HS children undergoing first HSCT at the Royal Manchester Children's Hospital or the University of Minnesota Children's Hospital from 1983 to 2016. Implementation of busulfan pharmacokinetic monitoring started in 2004 in both institutions. Two hundred and forty HS children were included in this analysis (historical era (pre-2004), n=131; current era (post 2004), n=109). The proportion of patients with graft failure was significantly lower in the current era compared with the historical era (37.2% vs 10.1%, respectively). Of 49 patients with graft failure in the historical era, 1 had aplasia and 48 had autologous reconstitution. All the 11 graft failures of the current era occurred in recipients of cord blood transplants (7 aplasia and 4 autologous reconstitution). The outcomes of second transplant in these patients has improved, with 89% of such patients alive and engrafted in the current era compared with 58% in the historical era. The pattern of graft failure has changed from autologous reconstitution, likely secondary to inadequate myelosuppression in the historical era, to aplasia in the current era, likely due to imperfect immunosuppression.

Guideline: HLA matching and donor selection for haematopoietic progenitor cell transplantation

A review of the British Society for Histocompatibility and Immunogenetics (BSHI) "Guideline for selection and HLA matching of related, adult unrelated donors and umbilical cord units for haematopoietic progenitor cell transplantation" 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.

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

A review of the British Society for Histocompatibility and Immunogenetics (BSHI) "Guideline for selection and HLA matching of related, adult unrelated donors and umbilical cord units for haematopoietic progenitor cell transplantation" 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.

In vivo T-cell depletion using alemtuzumab in family and unrelated donor transplantation for pediatric non-malignant disease achieves engraftment with low incidence of graft vs. host disease.

In vivo T-cell depletion, using alemtuzumab therapy prior to SCT, can reduce the incidence of GVHD. This treatment has a potential to delay immune reconstitution resulting in increased morbidity due to viral illnesses. We retrospectively analyzed data on all pediatric patients with non-malignant disorders who received alemtuzumab-based conditioning regimens in our center over the last 10 yr (n = 91). Our data show an OS of 91.2%. The incidence of acute (grade 2-4) GVHD was 18.7% and that of chronic GVHD 5.5%. Viremia due to adenovirus, EBV and CMV was seen in 19.8%, 64.8% and 39.6% patients, respectively, with only two deaths attributed to viral infection (adenovirus). Chimerism level at three month was predictive of graft outcome. Nine patients, who had graft failure after first SCT, were salvaged with a second SCT using RIC and same donor (if available). Based on these results, we conclude that the use of in vivo T-cell depletion is safe, achieves good chimerism and does not lead to increased morbidity and mortality due to viral infections. It is associated with a reduced incidence of chronic GVHD.

A group-specific sequencing approach to investigate the presence of atypical human leucocyte antigen alleles.

Accurate human leucocyte antigen (HLA) typing results are essential in determining the degree of compatibility between donor and recipient in both solid organ (SO) and hematopoietic stem cell (HSC) transplantation. Current HLA typing methodologies can generate ambiguous results which may need resolving. This group-specific sequencing approach allowed investigation into the presence of the low expressor HLA-A*24:02:01:02L allele and the rare HLA-A*02:64 allele in a SO transplant recipient and a HSC transplant recipient, respectively. Locus-specific amplification of HLA-A was performed. Exons 2 and 3 were sequenced in both directions followed by group-specific sequencing to resolve ambiguities. Hemizygous sequence data of intron 2 generated from the HLA-A*24 allele indicated the presence of the HLA-A*24:02:01:01 allele. HLA-A*02:64 was identified by sequencing the allele in isolation over exons 2 and 3 and allowed confirmation of this allele sequence with the IMGT/HLA database (Accession number AY297166). This approach is cost efficient and can be modified to sequence alleles at other HLA loci. It has also been adapted to characterize the novel HLA-DQB1*06:48 allele (Accession number HE647646) as well as the non-HLA gene, UGT2B17, making it a useful tool to augment existing typing methodologies.

Assessment of the purity of isolated cell populations for lineage-specific chimerism monitoring post haematopoietic stem cell transplantation.

Following haematopoietic stem cell transplantation, monitoring the proportion of donor and recipient haematopoiesis in the patient (chimerism) is an influential tool in directing further treatment choices. Short tandem repeat (STR) analysis is a method of chimerism monitoring using DNA isolated from peripheral blood, bone marrow or specific isolated cell lineages such as CD3+ T cells. For lineage-specific STR analysis on cell populations isolated from peripheral blood, a qualitative estimation of the purity of each isolated population is essential for the correct interpretation of the test data. We describe a rapid, inexpensive method for the determination of purity using a simple flow cytometry method. The method described for assessing the purity of sorted CD3+ cells can be applied to any cell population isolated using the same technology. Data obtained were comparable to results from a commercial polymerase chain reaction (PCR)-based method for the assessment of purity (Non-T Genomic Detection Kit, Accumol, Calgary, AB, Canada) (P = 0.59). Of the 303 samples tested by flow cytometry, 290 (95.7%) exceeded 90% purity, and 215 (70.95%) were over 99% pure. There were some outlying samples, showing diversity between samples and the unpredictability of purity of isolated cell populations. This flow cytometry method can be easily assimilated into routine testing protocols, allowing purity assessment in multiple-sorted cell populations for lineage-specific chimerism monitoring using a single secondary antibody and giving results comparable to a PCR-based method. As purity of isolated cell lineages is affected by time after venepuncture and storage temperature, assessment of each sample is recommended to give a reliable indication of sample quality and confidence in the interpretation of the results.

Increased severity of acute graft versus host disease as a result of differential expression following a homozygous gene deletion.

Acute graft versus host disease (aGvHD) is a major cause of early morbidity post-haematopoietic stem cell transplantation with minor histocompatibility antigens being a contributing factor. One mHA encoded by the UDP glycosyltransferase 2 family polypeptide B17 (UGT2B17) gene has been shown to be immunogenic because of differential expression in the donor and recipient. We investigated the effects of a homozygous gene deletion of UGT2B17 on the severity of acute aGvHD post-HSCT in HLA-matched related donors. 115 donor and recipient HLA and UGT2B17 genotypes were determined using PCR-SSO and PCR-SSP, respectively. aGvHD grading was determined using routine criteria and dichotomized into either nonclinically significant (0-I) or clinically significant (II-IV). For all analyses, P-values of ≤ 0.05 were considered significant. The frequency of the gene deletion within the total cohort tested was 29.1%. A significant increase in aGvHD severity (grades II-IV) was seen in UGT2B17 recipients expressing the protein when transplanted with a UGT2B17 disparate donor (P = 0.011). We observed a significant association between UGT2B17 expressing recipients and UGT2B17 deficient donors with the severity of aGvHD. This study provides additional evidence that genomic variations may predispose to more severe aGvHD, but are not a mechanism for GvHD.

Characterization of the novel HLA-DQB1*06:48 allele by group-specific sequencing.

HLA-DQB1*06:48 has single nucleotide polymorphisms within codons 70 and 62 of exon 2 (GGG>AGG and AAG>AAC) relative to HLA-DQB1*06:02:01 and HLA-DQB1*06:37. This results in amino acid differences (G>R and K>N) that will change the polarity and charge of the encoded antigen and may therefore affect its peptide repertoire.

Donor CD31 genotype and its association with acute graft-versus-host disease in HLA identical sibling stem cell transplantation.

CD31 gene polymorphisms are implicated in the pathogenesis of graft-versus-host disease (GvHD) following haematopoietic stem cell transplantation (HST). We investigated the influence of CD31 genotype on the incidence of GvHD following HST from an human leukocyte antigen (HLA)-identical sibling donor. Donor and recipient CD31 codons 125, 563 and 670 DNA polymorphisms were determined in 85 cases of HLA identical sibling HST from two transplant centres. A correlation between CD31 genotype and acute GvHD was considered significant if observed in patients from both transplant centres independently. A strong correlation was identified between donor CD31 codon 125 genotype and the incidence of acute GvHD. Acute GvHD grades II-IV occurred in 27 of 46 (59%) recipients with a CD31 codon 125 leucine / valine heterozygous donor compared to nine of 39 (23%) recipients with a CD31 codon 125 homozygous donor (P=0.0019, relative-risk 2.45, 95% confidence interval 1.3-4.5). This correlation was significant in patients from both transplant centres (P=0.015 and P=0.019). We suggest that CD31 genotype may influence the function of donor-derived leukocytes and may be informative when there is a choice of comparable donors.

Mannose binding lectin and FcgammaRIIa (CD32) polymorphism in Spanish systemic lupus erythematosus patients.

OBJECTIVE: Mannose binding lectin (MBL) and FcgammaRII (CD32) polymorphisms have both been implicated as candidate susceptibility genes in systemic lupus erythematosus (SLE). The aim of this study was to evaluate the relationship of these polymorphisms with SLE. METHODS: We studied a cohort of 125 SLE patients from Barcelona, Spain and 138 geographically matched controls. Sequence-specific primer-polymerase chain reaction (SSP-PCR) amplification was used to determine CD32 and MBL structural polymorphisms. MBL haplotypes were established using sequence-specific oligonucleotide probing techniques. RESULTS: Patients carried the MBL codon 54 mutant allele more frequently than controls [odds ratio (OR) 2.2; 95% confidence interval (CI) 1.2-4.0; P=0.007] and the haplotype HY W52 W54 W57 was found to be significantly lower in cases compared with controls (OR 0.6; 95% CI 0.4-0.9; P=0.016). CONCLUSION: The MBL gene codon 54 mutant allele appears to be a risk factor for SLE, whilst haplotypes encoding for high levels of MBL are protective against the disease. Differences between controls and patients were not significant when considering the FcgammaRIIa polymorphisms; similar results were observed for renal affectation.

The influence of transforming growth factor-beta1 gene polymorphisms on the severity of gingival overgrowth associated with concomitant use of cyclosporin A and a calcium channel blocker.

BACKGROUND: The purpose of this study was to determine whether the prevalence and severity of gingival overgrowth in renal transplant recipients concomitantly treated with cyclosporin and a calcium channel blocker was associated with functional polymorphisms within the signal sequence of the transforming growth factor-(TGF)beta1 gene. METHODS: The extent and severity of gingival overgrowth for 164 renal transplant recipients immunosuppressed with cyclosporin A and concomitantly taking a calcium channel blocker since transplant were entered into the study (86 in Manchester, 78 in Belfast). Two biallelic polymorphisms of the TGF-beta1 gene were studied at position +869, codon 10 (leucine to proline substitution), and position +915, codon 25 (arginine to proline substitution). RESULTS: Subjects who were homozygous for proline at codon 10 had significantly higher overgrowth scores than those who were heterozygous (P= 0.03) or homozygous for leucine (P= 0.01). Subjects who were heterozygous (arginine/proline) at codon 25 had a significantly higher (P= 0.04) gingival overgrowth score than those who were homozygous for arginine. Logistic regression analysis indicated that for codon 25 independent predictors of severe gingival overgrowth were the heterozygous arginine/proline genotype (P= 0.009) and whether the individual was young (P= 0.05). CONCLUSIONS: Polymorphisms in the TGF-beta1 gene influence the expression of gingival overgrowth in renal transplant recipients concomitantly treated with cyclosporin and a calcium channel blocker. The polymorphism in the TGF-beta1 gene at codon 25 represented an independent genetic determinant of severe gingival overgrowth in the susceptible subjects studied.

Independent association of rheumatoid factor and the HLA-DRB1 shared epitope with radiographic outcome in rheumatoid arthritis.

OBJECTIVE: Findings of a recent study suggested that HLA-DRB1 alleles encoding the rheumatoid arthritis (RA) "shared epitope" (SE) were not predictive of erosive damage at 2 years in patients with early inflammatory arthritis who were rheumatoid factor (RF) positive, but were predictive in those who were RF negative. The present study was undertaken to determine whether RF status was also important in the association between the SE and radiographic outcome in patients with longstanding RA. METHODS: The association between radiographic outcome, HLA-DRBI, and RF status was examined in 299 RA patients with established disease (5-30 years). Radiographic outcome was measured by scoring radiographs of the hands and feet using the standard radiographs of Larsen. HLA-DRB1 typing was performed using polymerase chain reaction methodology. Results were stratified by RF status and analyzed by multiple regression. RESULTS: An association between radiographic severity and the SE was found in RF-, but not RF+, patients. RF- patients carrying an SE allele had higher Larsen scores than RF- patients lacking the SE, although there was no association with SE dosage. The mean Larsen score was significantly higher in RF+ patients than in RF- patients, but there were no differences between RF+ patients with 0, 1, or 2 SE alleles. Multiple regression analysis confirmed independent associations of RF and SE positivity with radiographic outcome. No significant associations were found between RF and the SE, or RF and individual SE alleles. CONCLUSION: Our data indicate that RF and the SE are independently associated with radiographic outcome in RA. In RF+ patients with longstanding RA, there is no apparent association between the presence of the SE and radiographic damage. However, in RF-patients, although radiographic outcome is generally less severe, there is an association between severity and presence of the SE.

Mannose-binding lectin gene polymorphisms as a susceptibility factor for chronic necrotizing pulmonary aspergillosis.

It was investigated whether a deficiency of mannose-binding lectin (MBL), which binds Aspergillus species avidly in vitro, could account for chronic necrotizing pulmonary aspergillosis (CNPA), which is seen most commonly in nonimmunocompromised patients. Blood samples were obtained from 11 patients (10 white) with CNPA and were compared with blood samples from 82 white control subjects. MBL haplotype profiles were determined by polymerase chain reaction, using sequence-specific primers and sequence-specific oligonucleotide probing techniques. Seven of the 10 white patients with CNPA had MBL haplotypes that encode for low levels of the protein, compared with 25.6% of the white control subjects (P=.004). Presence of the codon 52 mutation was particularly common in patients with CNPA (P=.015), which suggests a greater involvement of this mutation.

Short-form HLA-DP typing with 48 primer mixes using the polymerase chain reaction and sequence-specific primers.

We have developed a short-form SSP-based HLA-DP typing system for routine use adapted from a comprehensive HLA-DP typing method described by Gilchrist et at. (1998). Our short-form system detects 93 alleles, including the 18 most common HLA-DPB1 alleles and eight HLA-DPA1 alleles. The primer mixes described were tested using the PCR-SSP Manager (Bunce et al., 1998) database to confirm the specificity of selected primers, and to detect potentially ambiguous amplifications. This short-form HLA-DP typing system was validated using 50 fully typed samples obtained through the UCLA International DNA Exchange. All samples gave 100% concordance with the consensus type. Our laboratory routinely uses a PCR-SSP based system of 48 primer mixes for HLA-DRB and HLA-DQB typing. The advantage of the short-form HLA-DP typing system described here is that the additional 48 HLA-DP primer mixes required can be included on the second half of a 96-well format tray. This method now enables a full HLA class II typing at the level of allele group resolution in 2 1/2 h.

Mannose binding lectin (MBL) genotype distributions with relation to serum levels in UK Caucasoids.

Mannose binding lectin (MBL) gene and promoter-region polymorphisms contribute to a reduction in the levels of circulating MBL in a number of ways. Promoter polymorphisms affect the levels of MBL produced, whilst structurally encoding mutations cause non-functional protein to be assembled and subsequently degraded. MBL is important as a protein of the innate immune system in both the clearance of potential pathogens and the activation of the complement cascade. Using variations of SSP-PCR amplifications and SSO probing techniques, we have produced MBL-polymorphism haplotype and genotype profiles of a series of high-level MBL-producing, low-level MBL-producing and random individuals taken from a population of 800 UK Caucasoid controls. Structurally encoding mutant alleles were more frequent within the low-level producing cohort when compared to both high-level producers and the randomly selected sample. However, not all low-level producers could be accounted for by the possession of low-level encoding haplotypes. This may be due to the presence of additional, undetected polymorphisms governing MBL production, or another external factor that may influence the transcriptional regulation of the gene.