Transient anti-cytokine autoantibodies superimpose the hyperinflammatory response in Kawasaki disease and multisystem inflammatory syndrome in children: a comparative cohort study on correlates of disease.

Background: Children with SARS-CoV-2 related Multisystem Inflammatory Syndrome in Children (MIS-C) often present with clinical features that resemble Kawasaki disease (KD). Disease severity in adult COVID-19 is associated to the presence of anti-cytokine autoantibodies (ACAAs) against type I interferons. Similarly, ACAAs may be implicated in KD and MIS-C.

B-cell targeting with anti-CD38 daratumumab: implications for differentiation and memory responses.

B cell-targeted therapies, such as CD20-targeting mAbs, deplete B cells but do not target the autoantibody-producing plasma cells (PCs). PC-targeting therapies such as daratumumab (anti-CD38) form an attractive approach to treat PC-mediated diseases. CD38 possesses enzymatic and receptor capabilities, which may impact a range of cellular processes including proliferation and differentiation.

Immunodeficiency, autoimmunity, and increased risk of B cell malignancy in humans with mutations.

Tumor necrosis factor receptor-associated factor 3 (TRAF3) is a central regulator of immunity. TRAF3 is often somatically mutated in B cell malignancies, but its role in human immunity is not defined. Here, in five unrelated families, we describe an immune dysregulation syndrome of recurrent bacterial infections, autoimmunity, systemic inflammation, B cell lymphoproliferation, and hypergammaglobulinemia.

Hematopoietic stem cell transplantation in a patient with proteasome-associated autoinflammatory syndrome (PRAAS).

Background: Proteasome-associated autoinflammatory syndromes (PRAASs) form a family of recently described rare autosomal recessive disorders of disturbed proteasome assembly and proteolytic activity caused by mutations in genes coding for proteasome subunits. The treatment options for these proteasome disorders consist of lifelong immunosuppressive drugs or Janus kinase inhibitors, which may have partial efficacy and noticeable side effects. Because proteasomes are ubiquitously expressed, it is unknown whether hematopoietic stem cell transplantation (HSCT) may be a sufficient treatment option.

Activated neutrophils exert myeloid-derived suppressor cell activity damaging T cells beyond repair.

Myeloid-derived suppressor cells (MDSCs) have the capacity to suppress T-cell-mediated immune responses and impact the clinical outcome of cancer, infections, and transplantation settings. Although MDSCs were initially described as bone marrow-derived immature myeloid cells (either monocytic or granulocytic MDSCs), mature neutrophils have been shown to exert MDSC activity toward T cells in ways that remain unclear. In this study, we demonstrated that human neutrophils from both healthy donors and cancer patients do not exert MDSC activity unless they are activated.

High-throughput compound screen reveals mTOR inhibitors as potential therapeutics to reduce (auto)antibody production by human plasma cells.

Antibody production by the B cell compartment is a crucial part of the adaptive immune response. Dysregulated antibody production in the form of autoantibodies can cause autoimmune disease. To date, B-cell depletion with anti-CD20 antibodies is commonly applied in autoimmunity, but pre-existing plasma cells are not eliminated in this way.

Neutrophils acquire antigen-presenting cell features after phagocytosis of IgG-opsonized erythrocytes.

Neutrophils are particularly well known for their antimicrobial function. Although historically they are regarded as strictly a phagocyte of the innate immune system, over time it has become clear that neutrophils are versatile cells with numerous functions including innate and adaptive immune regulation. We have previously described a role for human neutrophils in antibody-mediated red blood cell (RBC) clearance.

Pathogenic NFKB2 variant in the ankyrin repeat domain (R635X) causes a variable antibody deficiency.

Genetic studies are identifying an increasing number of monogenic causes of Common Variable Immunodeficiency (CVID). Pathogenic variants in the C-terminus of NFKB2 have been identified in the subset of CVID patients whose immunodeficiency is associated with ectodermal dysplasia and central adrenal insufficiency. We describe 2 unrelated CVID pedigrees with 4 cases of pathogenic stop gain variants (c.

Loss-of-function nuclear factor κB subunit 1 (NFKB1) variants are the most common monogenic cause of common variable immunodeficiency in Europeans.

Background: The genetic cause of primary immunodeficiency disease (PID) carries prognostic information.

Objective: We conducted a whole-genome sequencing study assessing a large proportion of the NIHR BioResource-Rare Diseases cohort.

Methods: In the predominantly European study population of principally sporadic unrelated PID cases (n = 846), a novel Bayesian method identified nuclear factor κB subunit 1 (NFKB1) as one of the genes most strongly associated with PID, and the association was explained by 16 novel heterozygous truncating, missense, and gene deletion variants.

Humoral Immunodeficiency with Hypotonia, Feeding Difficulties, Enteropathy, and Mild Eczema Caused by a Classical Mutation.

We describe here the case of a boy who presented with pulmonary infections, feeding difficulties due to velopharyngeal insufficiency and gastroesophageal reflux, myopathy, and hypotonia soon after birth. Later, he was also found to have an elevated immunoglobulin (Ig) E and mild eczema and was diagnosed with inflammatory bowel disease. Further immunological screening at the age of 7 years showed low B and NK cell numbers but normal CD4 and CD8 T cells and notably, normal numbers of CD4 regulatory T (Treg) cells.

Mutations in EXTL3 Cause Neuro-immuno-skeletal Dysplasia Syndrome.

EXTL3 regulates the biosynthesis of heparan sulfate (HS), important for both skeletal development and hematopoiesis, through the formation of HS proteoglycans (HSPGs). By whole-exome sequencing, we identified homozygous missense mutations c.1382C>T, c.

Phenotypic and Functional Comparison of Class Switch Recombination Deficiencies with a Subgroup of Common Variable Immunodeficiencies.

Primary antibody deficiencies (PADs) are the most common immunodeficiency in humans, characterized by low levels of immunoglobulins and inadequate antibody responses upon immunization. These PADs may result from an early block in B cell development with a complete absence of peripheral B cells and lack of immunoglobulins. In the presence of circulating B cells, some PADs are genetically caused by a class switch recombination (CSR) defect, but in the most common PAD, common variable immunodeficiency (CVID), very few gene defects have as yet been characterized despite various phenotypic classifications.

Varicella vaccination in pediatric oncology patients without interruption of chemotherapy.

Background: Morbidity and mortality from primary varicella-zoster virus (VZV) infection is increased in immunocompromised children. Vaccination of VZV-seronegative cancer patients with live-attenuated varicella vaccine is safe when chemotherapy is interrupted. However, VZV vaccination without interruption of chemotherapy would be preferable.

Phenotypic variation in Aicardi-Goutières syndrome explained by cell-specific IFN-stimulated gene response and cytokine release.

Aicardi-Goutières syndrome (AGS) is a monogenic inflammatory encephalopathy caused by mutations in TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR1, or MDA5. Mutations in those genes affect normal RNA/DNA intracellular metabolism and detection, triggering an autoimmune response with an increase in cerebral IFN-α production by astrocytes. Microangiopathy and vascular disease also contribute to the neuropathology in AGS.

Fetal exposure to HIV-1 alters chemokine receptor expression by CD4+T cells and increases susceptibility to HIV-1.

Absolute numbers of lymphocytes are decreased in uninfected infants born to HIV-1-infected women (HIV-1-exposed). Although the exact mechanism is unknown, fetal exposure to maternal HIV-1-infection could prime the immune system and affect T cell trafficking. We compared the expression of chemokine receptors on cord blood CD4(+) T cells from HIV-1-exposed children and healthy controls.

Aicardi-Goutières syndrome harbours abundant systemic and brain-reactive autoantibodies.

Objectives: Aicardi-Goutières syndrome (AGS) is an autoimmune disorder that shares similarities with systemic lupus erythematous. AGS inflammatory responses specially target the cerebral white matter. However, it remains uncertain why the brain is the most affected organ, and little is known about the presence of autoantibodies in AGS.

Failure to detect functional neutrophil B helper cells in the human spleen.

A novel role for human neutrophilic granulocytes was recently described, showing that these cells, upon entering the spleen, can be reprogrammed into a distinct B cell-helper neutrophil phenotype that is capable of eliciting B cell responses such as immunoglobulin secretion, class switch recombination and somatic hypermutation. Using similar protocols, we detected a homogeneous population of CD15(high)CD16(high) neutrophils in fresh human spleen samples, which did not differ in phenotype and function from blood neutrophils. No phenotypic characteristics of costimulatory nature were detected on splenic or circulating neutrophils, nor could we reproduce the immunoglobulin production of splenic B cells in the presence of splenic neutrophils, although B cell function and neutrophil activity were normal.

Aberrant humoral immune reactivity in DOCK8 deficiency with follicular hyperplasia and nodal plasmacytosis.

Mutations in the DOCK8 gene define the most common form of autosomal-recessive Hyper-IgE-syndrome (AR-HIES/OMIM#243700). In a patient with extensive molluscum contagiosum lesions, a homozygous DOCK8 gene deletion was demonstrated. In-vivo 18-FDG uptake showed multiple non-enlarged lymph nodes without uptake in the spleen.

Identification of B cell defects using age-defined reference ranges for in vivo and in vitro B cell differentiation.

Primary immunodeficiencies consist to a large extent of B cell defects, as indicated by inadequate Ab levels or response upon immunization. Many B cell defects have not yet been well characterized. Our objective was to create reliable in vivo and in vitro assays to routinely analyze human B cell differentiation, proliferation, and Ig production and to define reference ranges for different age categories.

A reversion of an IL2RG mutation in combined immunodeficiency providing competitive advantage to the majority of CD8+ T cells.

Mutations in the common gamma chain (γc, CD132, encoded by the IL2RG gene) can lead to B(+)T(-)NK(-) X-linked severe combined immunodeficiency, as a consequence of unresponsiveness to γc-cytokines such as interleukins-2, -7 and -15. Hypomorphic mutations in CD132 may cause combined immunodeficiencies with a variety of clinical presentations. We analyzed peripheral blood mononuclear cells of a 6-year-old boy with normal lymphocyte counts, who suffered from recurrent pneumonia and disseminated mollusca contagiosa.

Chronic exposure of astrocytes to interferon-α reveals molecular changes related to Aicardi-Goutieres syndrome.

Aicardi-Goutières syndrome is a genetically determined infantile encephalopathy, manifesting as progressive microcephaly, psychomotor retardation, and in ∼25% of patients, death in early childhood. Aicardi-Goutières syndrome is caused by mutations in any of the genes encoding TREX1, RNASEH2-A, -B, -C and SAMHD1, with protein dysfunction hypothesized to result in the accumulation of nucleic acids within the cell, thus triggering an autoinflammatory response with increased interferon-α production. Astrocytes have been identified as a major source of interferon-α production in the brains of patients with Aicardi-Goutières syndrome.