Prognostic Value of Colonic Tissue and Blood Eosinophils in Ulcerative Colitis.

BACKGROUND It has been suggested that eosinophils may be a prognostic marker of disease outcome in ulcerative colitis (UC), but conflicting data exist. The objective was to investigate the extent of mucosal eosinophils and peripheral blood eosinophil count in newly diagnosed UC patients and to investigate its predictive value in short- and long-term disease outcomes. METHODS The degree of eosinophilia in baseline colonic biopsies and blood of newly diagnosed UC patients was retrospectively analyzed. It was investigated if tissue and blood eosinophilia could be a marker of a severe phenotype of UC, defined as the need for corticosteroids or immunomodulators in the first year or treatment with therapeutic monoclonal antibodies or colectomy during follow-up. Time to therapeutic monoclonal antibodies and time to colectomy were also evaluated as outcomes. RESULTS There were 103 UC patients (median age 26 years) included. Median tissue peak eosinophil count (PEC) was 70.0 and median peripheral blood eosinophil count was 0.3 × 109/L at diagnosis. Tissue PEC (r = -0.161, P = .104) and blood eosinophil count (r = 0.022, P = .877) were not correlated with the severity of histologic inflammation. Logistic regression analyses did not identify PEC and blood eosinophil count as predictors of more severe disease outcomes. Tissue PEC and peripheral blood eosinophil count did not predict the time the initiation of therapeutic monoclonal antibodies or colectomy. CONCLUSION Baseline tissue or peripheral blood eosinophils are not markers of disease activity and cannot be used as a predictor of severe disease outcomes in both adults and children with UC

A modeling approach for mean fluorescence intensity value harmonization and cutoff prediction for luminex single antigen bead assays of two different vendors

Luminex single antigen bead (SAB) kits from One Lambda (OL) and Lifecodes (LC) are widely used for HLA antibody detection but have substantial differences in design and assay protocol resulting in different mean fluorescence intensity (MFI) values. Here, we present a non-linear modeling approach to accurately convert MFI values between two vendors and to establish user-independent MFI cutoffs when analyzing big datasets. HLA antibody data from a total of 47 EDTA-treated sera tested using both OL and LC SAB kits were analyzed. MFI comparisons were made for the common 84 HLA class I and 63 class II beads. In the exploration set (n = 24), a non-linear hyperbola model on raw MFI corrected by locus-specific highest self MFI subtraction yielded the highest correlation (class I r2: 0.946, class II r2: 0.898). Performance of the model was verified in an independent validation set (n = 12) (class I r2: 0.952, class II r2: 0.911). Furthermore, in an independent cohort of post-transplant serum samples (n = 11) using the vendor-specific MFI cutoffs dictated by the current model, we found 94% accuracy in bead-specific reactivity assignments by the two vendors. We recommend using the non-linear hyperbola modeling approach with self HLA correction and locus-specific analyzes to harmonize MFI values between two vendors in particular research datasets. As there are considerable variations between the two assays, using MFI conversion for individual patient samples is not recommended.</p

Association between CTL Precursor Frequency to HLA-C Mismatches and HLA-C Antigen Cell Surface Expression

Previous studies showed the relevance of the cytotoxic T-cell precursor (CTLp) frequency assay for prediction of the outcome of HLA mismatched hematopoietic cell transplantation (HCT). Recently, it has been shown that HLA-C cell surface expression is correlated with virus specific cytotoxic T-cell responses and viremia control in HIV patients. The aim of the current study was to investigate the association between HLA-C antigen expression and the CTLp frequency to the mismatched HLA-C antigen. In total 115 recipient–donor pairs, for whom a successful CTLp assay was performed, were evaluated for this pilot study. All donor–recipient pairs were matched at 9/10 alleles with a single mismatch at the HLA-C locus. Antigen expression level of the mismatched HLA-C allele for each recipient and donor was based on the mean fluorescence intensity (MFI) values as described by Apps et al. (1). The cell surface expression of recipient’s mismatched HLA-C antigen was significantly lower among CTLp negative (n = 59) compared to CTLp positive (n = 56) pairs (154 and 193 MFI units, respectively, p = 0.0031). This difference was more pronounced in donor–recipient pairs that were mismatched for amino-acid residue-116 located in the groove of the HLA-C antigen, suggesting that the importance of peptide binding in the allo-recognition. Furthermore, in the particular case of low expression of the recipient mismatched HLA-C antigen (MFI < 115), CTLp reactivity depended on HLA-C expression level in the donor, the median MFI of donor’s mismatched HLA-C antigen was 114 in CTLp negative cases (n = 26), while in CTLp positive cases (n = 15) the median MFI of donor’s HLA-C antigen was 193 (p = 0.0093). We conclude that the expression level of the donor and recipient mismatched HLA-C antigens affect CTLp outcome. HLA-C antigen expression levels in combination with the CTLp assay may prove useful for the prediction of the clinical outcome of HLA-C mismatched HCT

Ensuring HLA-matched platelet support requires an ethnic diverse donor population

BACKGROUND: Patients refractory for platelet transfusions benefit from human leukocyte antigen (HLA)-matched platelet transfusions. Differences in ethnic background of patients and donors could hamper the availability of sufficient numbers of HLA-matched donors for all patients. We evaluated our HLA-matched donor program and explored the role of ethnic background of patients related to the number of available donors. METHODS: We performed a cohort study among consecutive patients who received HLA-matched platelet concentrates in the Netherlands between 1994 and 2017. The number of available matched donors was determined per patient. Haplotypes were constructed from genotypes with computer software (PyPop). Based on haplotypes, HaploStats, an algorithm from the National Marrow Donor Program, was used to assess the most likely ethnic background for patients with 5 or fewer and 30 or more donors. RESULTS: HLA typing was available for 19,478 donors in September 2017. A total of 1206 patients received 12,350 HLA-matched transfusions. A median of 83 (interquartile range, 18-266) donors were available per patient. For 95 (10.3%) patients, 5 or fewer donors were available. These patients were more likely to have an African American background, whereas patients with 30 or more donors were more often from Caucasian origin, compared with Caucasian origin for patients with 30 donors. CONCLUSION: Adequate transfusion support could be guaranteed for most but not all refractory patients. More non-Caucasian donors are required to ensure the availability of HLA-matched donors for all patients in the Netherlands

HLA association in MOG-IgG- and AQP4-IgG-related disorders of the CNS in the Dutch population

OBJECTIVE: To investigate the possible human leukocyte antigen (HLA) association of both myelin oligodendrocyte glycoprotein (MOG-IgG)-associated diseases (MOGAD) and aquaporin-4 antibody (AQP4-IgG)-positive neuromyelitis optica spectrum disorders (NMOSDs) in the Dutch population with European ancestry to clarify similarities or differences in the immunogenetic background of both diseases. METHODS: Blood samples from patients in the Dutch national MS/NMOSD expert clinic were tested for MOG-IgG and AQP4-IgG using a cell-based assay. HLA Class I and II genotyping was performed in 43 MOG-IgG-seropositive and 42 AQP4-IgG-seropositive Dutch patients with European ancestry and compared with those of 5,604 Dutch healthy blood donors. RESULTS: No significant HLA association was found in MOG-IgG-seropositive patients. The AQP4-IgG-seropositive patients had a significant higher frequency of HLA-A*01 (61.9% vs 33.7%, OR 3.16, 95% CI, 1.707-5.863, p after correction [pc] = 0.0045), HLA-B*08 (61.9% vs 25.6%, OR 4.66, 95% CI, 2.513-8.643, pc < 0.0001), and HLA-DRB1*03 (51.2% vs 27.6%, OR 2.75, 95% CI, 1.495-5.042, pc = 0.0199) compared with controls. CONCLUSIONS: The present study demonstrates differences in the immunogenetic background of MOGAD and AQP4-IgG-positive NMOSD. The strong positive association with HLA-A*01, -B*08, and -DRB1*03 is suggestive of a role of this haplotype in the etiology of AQP4-IgG-positive NMOSD in patients with European ancestry, whereas in MOGAD no evidence was found for any HLA association in these disorders

A possible role for HLA-G in development of uteroplacental acute atherosis in preeclampsia

HLA-G, a non-classical HLA molecule expressed by extravillous trophoblasts, plays a role in the maternal immune tolerance towards fetal cells. HLA-G expression is regulated by genetic polymorphisms in the 3' untranslated region (3'UTR). Low levels of HLA-G in the maternal circulation and placental tissue are linked to preeclampsia. Our objective was to investigate whether variants of the 3'UTR of the HLA-G gene in mother and fetus are associated with acute atherosis, a pregnancy specific arterial lesion of the decidua basalis that is prevalent in preeclampsia. Paired maternal and fetal DNA samples from 83 normotensive and 83 preeclamptic pregnancies were analyzed. We sequenced the part of the HLA-G 3'UTR containing a 14-bp insertion/deletion region and seven single nucleotide polymorphisms (SNPs). Associations with acute atherosis were tested by logistic regression. The frequency of heterozygosity for the 14-bp polymorphism (Ins/Del) and the +3142 SNP (C/G) variant in the fetus are associated with acute atherosis in preeclampsia (66.7 % vs. 39.6 %, p = 0.039, and 69.0 % vs. 43.4 %, p = 0.024). Furthermore, the fetal UTR-3 haplotype, which encompasses the 14-bp deletion and the +3142G variant, is associated with acute atherosis in preeclampsia (15 % vs. 3.8 %, p = 0.016). In conclusion, HLA-G polymorphisms in the fetus are associated with acute atherosis. We hypothesize that these polymorphisms lead to altered HLA-G expression in the decidua basalis, affecting local feto-maternal immune tolerance and development of acute atherosis

Apparent Lack of BRAFV600E Derived HLA Class I Presented Neoantigens Hampers Neoplastic Cell Targeting by CD8+ T Cells in Langerhans Cell Histiocytosis

Langerhans Cell Histiocytosis (LCH) is a neoplastic disorder of hematopoietic origin characterized by inflammatory lesions containing clonal histiocytes (LCH-cells) intermixed with various immune cells, including T cells. In 50-60% of LCH-patients, the somatic BRAFV600E driver mutation, which is common in many cancers, is detected in these LCH-cells in an otherwise quiet genomic landscape. Non-synonymous mutations like BRAFV600E can be a source of neoantigens capable of eliciting effective antitumor CD8+ T cell responses. This requires neopeptides to be stably presented by Human Leukocyte Antigen (HLA) class I molecules and sufficient numbers of CD8+ T cells at tumor sites. Here, we demonstrate substantial heterogeneity in CD8+ T cell density in n = 101 LCH-lesions, with BRAFV600E mutated lesions displaying significantly lower CD8+ T cell:CD1a+ LCH-cell ratios (p = 0.01) than BRAF wildtype lesions. Because LCH-lesional CD8+ T cell density had no significant impact on event-free survival, we investigated whether the intracellularly expressed BRAFV600E protein is degraded into neopeptides that are naturally processed and presented by cell surface HLA class I molecules. Epitope prediction tools revealed a single HLA class I binding BRAFV600E derived neopeptide (KIGDFGLATEK), which indeed displayed strong to intermediate binding capacity to HLA-A*03:01 and HLA-A*11:01 in an in vitro peptide-HLA binding assay. Mass spectrometry-based targeted peptidomics was used to investigate the presence of this neopeptide in HLA class I presented peptides isolated from several BRAFV600E expressing cell lines with various HLA genotypes. While the HLA-A*02:01 binding BRAF wildtype peptide KIGDFGLATV was traced in peptides isolated from a

Composition of Human Skin Microbiota Affects Attractiveness to Malaria Mosquitoes

The African malaria mosquito Anopheles gambiae sensu stricto continues to play an important role in malaria transmission, which is aggravated by its high degree of anthropophily, making it among the foremost vectors of this disease. In the current study we set out to unravel the strong association between this mosquito species and human beings, as it is determined by odorant cues derived from the human skin. Microbial communities on the skin play key roles in the production of human body odour. We demonstrate that the composition of the skin microbiota affects the degree of attractiveness of human beings to this mosquito species. Bacterial plate counts and 16S rRNA sequencing revealed that individuals that are highly attractive to An. gambiae s.s. have a significantly higher abundance, but lower diversity of bacteria on their skin than individuals that are poorly attractive. Bacterial genera that are correlated with the relative degree of attractiveness to mosquitoes were identified. The discovery of the connection between skin microbial populations and attractiveness to mosquitoes may lead to the development of new mosquito attractants and personalized methods for protection against vectors of malaria and other infectious diseases

Allocation to highly sensitized patients based on acceptable mismatches results in low rejection rates comparable to nonsensitized patients

Whereas regular allocation avoids unacceptable mismatches on the donor organ, allocation to highly sensitized patients within the Eurotransplant Acceptable Mismatch (AM) program is based on the patient\'s HLA phenotype plus acceptable antigens. These are HLA antigens to which the patient never made antibodies, as determined by extensive laboratory testing. AM patients have superior long-term graft survival compared with highly sensitized patients in regular allocation. Here, we questioned whether the AM program also results in lower rejection rates. From the PROCARE cohort, consisting of all Dutch kidney transplants in 1995-2005, we selected deceased donor single transplants with a minimum of 1 HLA mismatch and determined the cumulative 6-month rejection incidence for patients in AM or regular allocation. Additionally, we determined the effect of minimal matching criteria of 1 HLA-B plus 1 HLA-DR, or 2 HLA-DR antigens on rejection incidence. AM patients showed significantly lower rejection rates than highly immunized patients in regular allocation, comparable to nonsensitized patients, independent of other risk factors for rejection. In contrast to highly sensitized patients in regular allocation, minimal matching criteria did not affect rejection rates in AM patients. Allocation based on acceptable antigens leads to relatively low-risk transplants for highly sensitized patients with rejection rates similar to those of nonimmunized individuals