HLA and immunological features of SARS-CoV-2-induced Guillain-Barré syndrome.

We report the clinical and immunological features in a case of SARS-CoV-2-induced Guillain-Barré syndrome (Si-GBS), suggesting that (1) Si-GBS can develop even after paucisymptomatic COVID-19 infection; (2) a distinctive cytokine repertoire is associated with this autoimmune complication, with increased CSF concentration of IL-8, and moderately increased serum levels of IL-6, IL-8, and TNF-α; (3) a particular genetic predisposition can be relevant, since the patient carried several HLA alleles known to be associated with GBS, including distinctive class I (HLA-A33) and class II alleles (DRB1*03:01 and DQB1*05:01). To the best of our knowledge, this is the first case of GBS in which SARS-CoV-2 antibodies were detected in the CSF, further strengthening the role of the virus as a trigger. In conclusion, our study suggests that SARS-CoV-2 antibodies need to be searched in the serum and CSF in patients with GBS living in endemic areas, even in the absence of a clinically severe COVID-19 infection, and that IL-8 pathway can be relevant in Si-GBS pathogenesis. Further studies are needed to conclude on the relevance of the genetic findings, but it is likely that HLA plays a role in this setting as in other autoimmune neurological syndromes, including those triggered by infections.

Polymorphism of the HLA system and weak antibody response to BNT162b2 mRNA vaccine.

The polymorphism of the HLA system has been extensively studied in COVID-19 infection, however there are no data about the role of HLA on vaccine response. We report here the HLA-A, -B, -C, and DRB1 allelic frequencies of n = 111 individuals after BNT162b2 mRNA vaccine, selected on the basis of lower antibody levels (<5% percentile) after the second dose among a total of n = 2569 vaccinees, and compare them with the frequencies of a reference population. We found that differences in the frequencies of the alleles HLA-A*03:01, A*33:03, B*58:01 and at least one haplotype (HLA-A*24:02~C*07:01~B*18:01~DRB1*11:04) are associated with a weaker antibody response after vaccination, together with the age of vaccinees. Our results might suggest a role played by some HLA alleles or haplotypes in antibody production after the BNT162b2 mRNA vaccine, giving insights into the tracking of potentially susceptible individuals across populations. Further studies are needed to better define our exploratory findings and dissect the role of HLA polymorphism on response to anti-COVID-19 vaccines.

Nonpermissive HLA-DPB1 disparity is a significant independent risk factor for mortality after unrelated hematopoietic stem cell transplantation.

The importance of donor-recipient human leukocyte antigen (HLA)-DPB1 matching for the clinical outcome of unrelated hematopoietic stem cell transplantation (HSCT) is controversial. We have previously described an algorithm for nonpermissive HLA-DPB1 disparities involving HLA-DPB1*0901,*1001,*1701,*0301,*1401,*4501, based on T-cell alloreactivity patterns. By revisiting the immunogenicity of HLA-DPB1*02, a modified algorithm was developed and retrospectively tested in 621 unrelated HSCTs facilitated through the Italian Registry for oncohematologic adult patients. The modified algorithm proved to be markedly more predictive of outcome than the original one, with significantly higher Kaplan-Meier probabilities of 2-year survival in permissive compared with nonpermissive transplantations (55% vs 39%, P = .005). This was the result of increased adjusted hazards of nonrelapse mortality (hazard ratio [HR] = 1.74; confidence interval [CI], 1.19-2.53; P = .004) but not of relapse (HR = 1.02; CI, 0.73-1.42; P = .92). The increase in the hazards of overall mortality by nonpermissive HLA-DPB1 disparity was similar in 10 of 10 (HR = 2.12; CI, 1.23-3.64; P = .006) and 9 of 10 allele-matched transplantations (HR = 2.21; CI, 1.28-3.80; P = .004), both in early-stage and in advanced-stage disease. These data call for revisiting current HLA matching strategies for unrelated HSCT, suggesting that searches should be directed up-front toward identification of HLA-DPB1 permissive, 10 of 10 or 9 of 10 matched donors.

Autoimmune thyroid disease in Libyan children and young adults with type 1 diabetes mellitus.

UNLABELLED: Diabetes mellitus is a common autoimmune endocrine disorder associated with organ-specific autoantibodies which are frequently detected at the time of diagnosis. Some of these antibodies are specific to the pancreas (GAD, IA2, ICA) while others are related to different autoimmune diseases. AIM OF THE STUDY: To define the prevalence of thyroid autoimmune disease in Libyan patients with type 1 diabetes mellitus (T1DM) since no similar studies have been performed in Libya. MATERIALS AND METHODS: Blood samples were collected from 218 patients with T1DM who are followed by the Pediatric Department, Tripoli Medical Center, Libya. All sera were analyzed in Italy (Laboratory of Immunopathology and Allergy, Udine). The patients were composed of 123 females (56.4%) and 95 males (43.6%), mean age 12.2 ± 4.6 years (range 2.1-24.5 years), mean duration of diabetes 4.7 ± 4.0 years (range 0.1-17.5 years). Sera were tested for anti-thyroperoxidase (TPO) and anti-thyroglobulin antibodies (TG). TSH and FT4 concentrations were measured in all subjects. GAD, IA-2 was also measured. RESULTS: Of the diabetic children, 23.4% were positive for anti-microsomal peroxidase antibodies (TPO-Ab) and 7.8% for antithyroglobulin antibodies (TG-Ab); whereas 6.9% of the patients were positive for both TPO-Ab and TG-Ab. Of the T1DM patients who were positive for TPO-Ab, 66.6% were females. The majority (57%) of the patients who were positive for TPO had diabetes for longer than 5 years. Five patients (2.3%) had evidence of subclinical hypothyroidism whereas two patients (0.9%) had overt hypothyroidism. Two patients had subclinical hyperthyroidism and two (0.9%) had overt hyperthyroidism. Interestingly, 16.2% of patients were positive for both thyroid and pancreatic antibodies. CONCLUSIONS: The prevalence of autoimmune thyroid disease in type 1 diabetic patients is higher than in the general population. A routine screening strategy should be implemented with the determination of anti-thyroid antibodies and TSH in type 1 diabetic patients, particularly in girls, and in patients with diabetes of more than 5 years duration. Patients who have positive TPO antibodies may need the assessment of thyroid function at shorter intervals.

A new HLA-B allele, HLA-B*35:481.

The novel allele HLA-B*35:481 differs from HLA-B*35:05:01 by two nucleotide substitution in exon 3.

Allelic HLA Matching and Pair Origin Are Favorable Prognostic Factors for Unrelated Hematopoietic Stem Cell Transplantation in Neoplastic Hematologic Diseases: An Italian Analysis by the Gruppo Italiano Trapianto di Cellule Staminali e Terapie Cellulari, Italian Bone Marrow Donor Registry, and Associazione Italiana di Immunogenetica e Biologia dei Trapianti.

HLA molecules are important for immunoreactivity in allogeneic hematopoietic stem cell transplantation (HSCT). The Gruppo Italiano Trapianto di Cellule Staminali e Terapie Cellulari, Italian Bone Marrow Donor Registry, and Associazione Italiana di Immunogenetica e Biologia dei Trapianti promoted a retrospective observational study to evaluate HLA matching and the impact of allelic HLA mismatching and non-HLA factors on unrelated Italian HSCT outcomes. From 2012 to 2015, 1788 patients were enrolled in the study. The average donor age was 29 years and the average recipient age was 49 years. As a conditioning regimen, 71% of the patients received myeloablative conditioning. For GVHD prophylaxis, 76% received either antithymocyte or anti-T lymphocyte globulin, cyclosporine A, and methotrexate. Peripheral blood was the stem cell source in 80%. The median duration of follow-up was 53 months. Regarding HLA matching, 50% of donor-recipient pairs were 10/10 matched, 38% had 1 mismatch, and 12% had 2 or more mismatches. A total of 302 pairs shared Italian origin. Four-year overall survival (OS), progression-free survival, GVHD-free relapse-free survival, and relapse rates were 49%, 40%, 22%, and 34%, respectively. The 4-year NRM was 27%, and the 100-day cumulative incidence of grade ≥II acute GVHD (aGVHD) was 26%. In multivariate analysis, 9/10 and ≤8/10 HLA allele-matched pairs were associated with worse OS (P = .04 and .007, respectively), NRM (P = .007 and P < .0001, respectively), and grade III-IV aGVHD (P = .0001 and .01, respectively). Moreover, the incidences of grade II-IV aGVHD (P = .001) and chronic GVHD (P = .002) were significantly lower in Italian pairs. In conclusion, 10/10 HLA matching is a favorable prognostic factor for unrelated HSCT outcome in the Italian population. Moreover, the presence of 2 HLA-mismatched loci was associated with a higher NRM (P < .0001) and grade II-IV aGVHD (P = .006) and a poorer OS (P = .001) compared with 1 HLA-mismatched locus in early or intermediate disease phases. Finally, we found that Italian donor and recipient origin is a favorable prognostic factor for GVHD occurrence.

Use of DPB1 T-cell epitope algorithm among italian transplant centers: A survey on behalf of Associazione Italiana di Immunogenetica e Biologia dei Trapianti.

The HLA-DPB1 locus has been demonstrated to have a significant role on patients' outcome after allogeneic HSCT, and the so-called T-cell epitope (TCE) algorithm has been incorporated in international guidelines for the selection of unrelated donors. The purpose of the present study is to measure, through a national survey conducted on behalf of the Associazione Italiana di Immunogenetica e Biologia dei Trapianti (AIBT), the extent of awareness and use of HLA-DPB1 TCE-based algorithms during the donor search. 89% of the HLA laboratories answered to a short questionnaire and the results showed a progressive increase of the laboratories typing DPB1 in patients and their potential donors during the search (from 44% to 79% during the 2010-2019 period) as well as the application of a TCE-based algorithm for the donor choice whenever possible (from 24% to 65% during the same period). The DP-permissiveness status is detailed in the official HLA typing report by 12%, 32% and 50% of laboratories in 2010, 2015 and 2019, respectively. The present data indicate an encouraging raise in the awareness of the HLA-DPB1 role in unrelated donor selection; noteworthy, mentioning the TCE-based permissiveness status in the HLA typing report of each potential unrelated donor represents a notable mean to raise awareness among transplant physicians and to support them in their task of choosing the best donor. Nonetheless, despite the compelling evidence of the predictive ability of TCE-based algorithms, further efforts are still needed to extend its application to all transplant centers in Italy.

High-resolution analysis of the HLA-A, -B, -C and -DRB1 alleles and national and regional haplotype frequencies based on 120 926 volunteers from the Italian Bone Marrow Donor Registry.

HLA genes are highly polymorphic and structurally complex. They are located in the major histocompatibility complex (MHC) on chromosome 6, and the frequency of alleles and haplotypes varies widely among human populations. In this paper, we calculated the allele and haplotype frequencies using the HLA data of more than 120 000 Italian unrelated bone marrow donors enrolled in the national registry (IBMDR) and typed them with a high-resolution (HR) method for the HLA-A, -B, -C and -DRB1 alleles. The allele frequency data were obtained by manual counting; haplotype frequencies were calculated using the expectation maximisation (EM) algorithm. The total numbers of observed alleles were 226 for HLA-A, 343 for HLA-B, 201 for HLA-C and 210 for HLA-DRB1, which account for 5.4%, 6.7%, 5.2% and 8.5%, respectively, of each locus allele (IPD-IMGT/HLA Database Release 3.32, April 2018). The three most frequent Italian haplotypes were HLA-A*01:01~B*08:01~C*07:01~DRB1*03:01 (2.5%), A*02:01~B*18:01~C*07:01~DRB1*11:04 (1.1%) and A*30:01~B*13:02~C*06:02~DRB1*07:01 (1.1%). Moreover, for a relevant subset of the examined population (>100 000 individuals), the birthplace was available, and thus, we grouped the frequency data based on the corresponding Italian geographic areas, describing the HLA specificity of the Italian regional populations. The haplotype frequencies were also compared between national and regional data, and we observed remarkable differences in the regional haplotype frequencies, particularly in Sardinia. This study represents a valid tool to identify a more efficient haematopoietic stem cell unrelated donor recruitment and selection strategy, as well as for population genetic and HLA-disease association fields.

HLA-DQ types of celiac disease in Libyan children with type 1 diabetes mellitus.

OBJECTIVE: To determine the genetic profile of celiac disease (CD) in Libyan children with type 1 diabetes as there are no data on the frequency of human leukocyte antigen (HLA)-related CD-predisposing genes in diabetic patients in Libya. METHODS: We randomly studied 218 Libyan type 1 diabetic children. The mean age was 12.2±4.6 years; 56% were female patients. The mean duration of diabetes was 4.7±4.0 years. All patients were screened for CD with IgA tissue-transglutaminase (tTG) and endomysium antibodies. Patients with positive immunological screen were programmed for a small-bowel biopsy. HLA-DRB1* and HLA-DQB1* were genotyped in all tTG-positive patients. RESULTS: Twenty-seven (12.4%) out of 218 patients with type1 diabetes had positive tTG, and 20 (9.2%) of these patients were positive for endomysium antibodies. Five patients (5/27) were already known cases of biopsy-proven CD. Biopsy was not performed in two patients. One biopsy result was normal, whereas 19 biopsies demonstrated morphological changes consistent with CD. Forty-eight percent of the anti-tTG-positive group were homozygous for HLA-DQ2, whereas 75% of biopsy-proven CD patients had HLA-DQ2, 21% had HLA-DQ2/DQ8, and 4% had HLA-DQ8. In addition, the majority (70%) carried HLA-DQ2 linkage with HLA-DRB1*03. CONCLUSION: Overall, biopsy-confirmed prevalence of CD was 11% (24 of 218). The present study confirms that CD in the Libyan type 1 diabetic population is high when compared with European and US studies, and for the first time we document that this population shares similar HLA-DQ2 genotype. This supports the theory regarding the role of the environment as an important factor in CD development in this part of the world.

Molecular RH blood group typing of serologically D-/CE+ donors: the use of a polymerase chain reaction-sequence-specific primer test kit with pooled samples.

The known presence of RHD blood group alleles in apparently D­ individuals who are positive for C or E antigens leads to an appropriate investigation for the RHD gene on the red blood cells (RBCs) of D­ blood donors, thus preventing their RBCs from immunizing D­ recipients. Ready-to-use polymerase chain reaction­sequence-specific primer (PCR-SSP) typing kits are available and allow single-sample results. The need to perform this testing on a large number of donors affiliated with the Transfusion Department of Udine (Northern Italy) led to the use of molecular genetic RH blood group typing with PCR-SSP test kits and DNA samples mixed in pools. From a population of 35,000 blood donors screened for D antigen by serologic typing, a total of 235 samples, distributed in pools of 5 DNA samples, were investigated. Positive results were reevaluated by opening the pools and retesting single samples. Validation of DNA-pool typing with commercial kits was done. Among 235 genotyped samples, 12 were found to be PCR positive (5.1%), exhibiting DEL genotype and RHD-CE-D hybrid alleles. Our data demonstrate that the use of a PCR-SSP commercial test kit with pooled samples is a helpful and valid method to correctly detect RHD alleles. As a consequence, we reclassified our donors as carriers of potentially immunogenic alleles.

Frequency of the HFE gene mutations in five Italian populations.

Genetic hemochromatosis is an autosomal recessive disorder characterized by iron overload and a variety of clinical manifestations such as liver cirrhosis and arthropathy. It is the most common genetic disease of northern European populations. The principal gene responsible for hereditary hemochromatosis, designated HFE, is located on chromosome 6 in the HLA region. The single point mutation 845A, changing cysteine at position 282 to tyrosine (C282Y), in this gene has been identified as the main genetic basis of hereditary hemochromatosis. Two other mutations, 187G, a histidine to aspartate at amino acid 63 (H63D), and 193T, a serine to cysteine at amino acid 65 (S65C), appear to be associated with milder forms of hereditary hemochromatosis. There is a high prevalence of the C282Y mutation in northern European populations, whereas in those of the Mediterranean basin the prevalence seems low and almost absent in Far East countries. This mutation seems usually to occur on the ancestral haplotype 7.1. Accordingly, a Celtic origin of this mutation has been suggested. The aim of this study was to determine the frequency of HFE gene mutations in five geographic regions in Italy. Samples were tested for C282Y, H63D, and S65C mutations of the HFE gene according to methods of each laboratory and the results were standardized with the exchange of typed samples between the different laboratories. In addition, C282Y-positive DNA samples were typed for D6S105 allele 8 and HLA-A3 by ARMS-PCR. We have found that the allele frequency of the C282Y mutation decreases from northeast Italy (Friuli, 6%) to northwest Italy (Piedmont, 4.8%) and to central Italy (Emilia-Romagna, 1.7%). However, this mutation is lacking in the two regions of the Mediterranean basin's center (Sicily and Sardinia). Accordingly, a significant difference in the frequency of the mutation was observed between these Italian regions (P = 0.07 x 10(-3)). In contrast, no difference was observed in allele frequency of H63D in the five Italian regions. Finally, as regards the S65C mutation a very low frequency was observed in Friuli, Emilia-Romagna, and Sardinia, whereas in Sicily and Piedmont we have not found this mutation. In conclusion, these data are consistent with the hypothesis that the C282Y mutation occurred in Caucasian populations of Celtic origin, whereas the H63D mutation is more ancient as demonstrated by the ubiquitous distribution.