SARS-CoV-2-specific T cell responses in patients with multisystem inflammatory syndrome in children.

Multisystem inflammatory syndrome in children (MIS-C) is a severe complication of SARS-CoV-2 infections that occurs in the pediatric population. We sought to characterize T cell responses in MIS-C compared to COVID-19 and pediatric hyperinflammatory syndromes. MIS-C was distinct from COVID-19 and hyperinflammatory syndromes due to an expansion of T cells expressing TRBV11-2 that was not associated with HLA genotype. Children diagnosed with MIS-C, but who were negative for SARS-CoV-2 by PCR and serology, did not display Vß skewing. There was no difference in the proportion of T cells that became activated after stimulation with SARS-CoV-2 peptides in children with MIS-C compared to convalescent COVID-19. The frequency of SARS-CoV-2-specific TCRs and the antigens recognized by these TCRs were comparable in MIS-C and COVID-19. Expansion of Vß11-2+ T cells was a specific biomarker of MIS-C patients with laboratory confirmed SARS-CoV-2 infections. Children with MIS-C had robust antigen-specific T cell responses to SARS-CoV-2.

Incidence and Risk Factors for Eosinophilia and Lung Disease in Biologic-Exposed Children With Systemic Juvenile Idiopathic Arthritis.

OBJECTIVE: Although interleukin-1 (IL-1)/IL-6 inhibitors are effective therapies for systemic juvenile idiopathic arthritis (JIA), some patients develop eosinophilia and lung disease during treatment. This study was undertaken to retrospectively evaluate incidence and risk factors for eosinophilia and describe lung disease outcomes in IL-1/IL-6 inhibitor-exposed patients with systemic JIA. METHODS: Among JIA patients at our institution exposed to interleukin-1 (IL-1)/IL-6 inhibitors (1995-2022), we compared incidence rate of eosinophilia in systemic JIA compared to other JIA, stratified by medication class (IL-1/IL-6 inhibitors, other cytokine inhibitors, methotrexate). We used Cox models to identify predictors of eosinophilia during IL-1/IL-6 inhibitor use and summarized treatment changes and outcomes after eosinophilia, including lung disease. HLA typing was performed on a clinical or research basis. RESULTS: There were 264 new medication exposures in 75 patients with systemic JIA and 41 patients with other JIA. A total of 49% of patients with systemic JIA with HLA typing (n = 45) were positive for HLA-DRB1*15 alleles. Eosinophilia was common during IL-1/IL-6 inhibitor use and did not differ by systemic JIA compared to other JIA (0.08 and 0.07 per person-year, respectively; P = 0.30). Among systemic JIA patients, pretreatment macrophage activation syndrome (MAS) was associated with a higher rate of subsequent eosinophilia on biologic therapy (unadjusted hazard ratio 3.2 [95% confidence interval 1.2-8.3]). A total of 4 of 5 patients who switched therapy within 10 weeks of eosinophilia experienced disease flare compared to none of the patients who continued the original therapy. A total of 8 of 25 patients with pulmonary evaluations had lung disease, and all had severe manifestations of systemic JIA (MAS, intensive care unit stay). One death was attributed to systemic JIA-lung disease. CONCLUSION: Eosinophilia is common in JIA patients using IL-1/IL-6 inhibitors. Severe disease may be associated with eosinophilia and lung disease in systemic JIA.

Comprehensive approach to high-resolution KIR typing.

Multiple studies suggest that prospective KIR typing may be beneficial for the outcome of bone marrow transplants, but to date no practical high-resolution KIR typing system has been developed. Here we propose a comprehensive high-resolution typing approach that provides allele level KIR typing. Based on the low-resolution typing obtained by SSO, the 14 KIR loci are divided in groups according to the level of polymorphism in exons coding for extracellular Ig-like domains and cytoplasmic tail. The first group is typed by sequence-specific oligonucleotide only; the second is typed by sequence-based typing (SBT) based on the amplification of a fragment coding the Ig-like domains; and the third is typed by SBT based on amplification of a fragment coding the cytoplasmic tail. SBT for the fourth group includes both the Ig-like and cytoplasmic domains. Because of a considerable number of polymorphisms scattered throughout all nine KIR exons, SBT results may still produce a number of ambiguities, which can be resolved by sequence-specific primers. This combined high-resolution approach was applied to the complete KIR typing of 205 Caucasian hematopoietic stem cell donors in support of the National Marrow Donor Program High-resolution KIR Typing Pilot Project. High-resolution typing of several KIR loci produced numerous novel alleles, whereas some loci demonstrated very limited polymorphism. Several of the novel alleles appeared in more than four donors, suggesting that these alleles are not rare. Our results showed that the comprehensive KIR typing approach presented here provides the balance of high-resolution typing and cost effectiveness.

HLA Class I and II Blocks Are Associated to Susceptibility, Clinical Subtypes and Autoantibodies in Mexican Systemic Sclerosis (SSc) Patients.

INTRODUCTION: Human leukocyte antigen (HLA) polymorphism studies in Systemic Sclerosis (SSc) have yielded variable results. These studies need to consider the genetic admixture of the studied population. Here we used our previously reported definition of genetic admixture of Mexicans using HLA class I and II DNA blocks to map genetic susceptibility to develop SSc and its complications. METHODS: We included 159 patients from a cohort of Mexican Mestizo SSc patients. We performed clinical evaluation, obtained SSc-associated antibodies, and determined HLA class I and class II alleles using sequence-based, high-resolution techniques to evaluate the contribution of these genes to SSc susceptibility, their correlation with the clinical and autoantibody profile and the prevalence of Amerindian, Caucasian and African alleles, blocks and haplotypes in this population. RESULTS: Our study revealed that class I block HLA-C*12:03-B*18:01 was important to map susceptibility to diffuse cutaneous (dc) SSc, HLA-C*07:01-B*08:01 block to map the susceptibility role of HLA-B*08:01 to develop SSc, and the C*07:02-B*39:05 and C*07:02-B*39:06 blocks to map the protective role of C*07:02 in SSc. We also confirmed previous associations of HLA-DRB1*11:04 and -DRB1*01 to susceptibility to develop SSc. Importantly, we mapped the protective role of DQB1*03:01 using three Amerindian blocks. We also found a significant association for the presence of anti-Topoisomerase I antibody with HLA-DQB1*04:02, present in an Amerindian block (DRB1*08:02-DQB1*04:02), and we found several alleles associated to internal organ damage. The admixture estimations revealed a lower proportion of the Amerindian genetic component among SSc patients. CONCLUSION: This is the first report of the diversity of HLA class I and II alleles and haplotypes Mexican patients with SSc. Our findings suggest that HLA class I and class II genes contribute to the protection and susceptibility to develop SSc and its different clinical presentations as well as different autoantibody profiles in Mexicans.

HLA class I and class II conserved extended haplotypes and their fragments or blocks in Mexicans: implications for the study of genetic diversity in admixed populations.

Major histocompatibility complex (MHC) genes are highly polymorphic and informative in disease association, transplantation, and population genetics studies with particular importance in the understanding of human population diversity and evolution. The aim of this study was to describe the HLA diversity in Mexican admixed individuals. We studied the polymorphism of MHC class I (HLA-A, -B, -C), and class II (HLA-DRB1, -DQB1) genes using high-resolution sequence based typing (SBT) method and we structured the blocks and conserved extended haplotypes (CEHs) in 234 non-related admixed Mexican individuals (468 haplotypes) by a maximum likelihood method. We found that HLA blocks and CEHs are primarily from Amerindian and Caucasian origin, with smaller participation of African and recent Asian ancestry, demonstrating a great diversity of HLA blocks and CEHs in Mexicans from the central area of Mexico. We also analyzed the degree of admixture in this group using short tandem repeats (STRs) and HLA-B that correlated with the frequency of most probable ancestral HLA-C/-B and -DRB1/-DQB1 blocks and CEHs. Our results contribute to the analysis of the diversity and ancestral contribution of HLA class I and HLA class II alleles and haplotypes of Mexican admixed individuals from Mexico City. This work will help as a reference to improve future studies in Mexicans regarding allotransplantation, immune responses and disease associations.