Lipopolysaccharide-responsive Beige-like Anchor Research Articles

Recessively Inherited LRBA Mutations Cause Autoimmunity Presenting as Neonatal Diabetes

Biallelic mutations in the human lipopolysaccharide responsive beige-like anchor (LRBA) gene lead to a primary immunodeficiency known as LRBA deficiency, characterized early-onset hypogammaglobulinemia, severe autoimmune manifestations, enteropathy, lymphoproliferation, and recurrent respiratory tract infections. Neonatal diabetes mellitus (NDM) has not been previously described in patients with LRBA mutations. In this study, the proband was diagnosed at 7 weeks of age with diabetes and additional autoimmunity and 3 other patients presented before 6 months of age. The other patients had diabetes onset between 6 and 12 months. Only 1 patient was positive for GAD antibody of those that were tested. However these patients had other autoimmune conditions including hematological manifestations, autoimmune enteropathy, and hypothyroidism. Identifying the underlying genetic etiology is clinically important for these patients as understanding the disease mechanism may allow the use of personalized therapy.

The profile of IL-4, IL-5, IL-10 and GATA3 in patients with LRBA deficiency and CVID with no known monogenic disease: Association with disease severity

BackgroundCommon variable immunodeficiency (CVID) is the most common symptomatic form of primary immunodeficiency (PID). LPS-responsive beige-like anchor protein (LRBA) deficiency is an autosomal recessive disease characterized by a CVID-like phenotype. T cell abnormality was reported in patients with CVID and LRBA deficiency. The study's aim was to evaluate IL-4, IL-5, IL-10 and GATA3 expression in patients with LRBA deficiency and CVID with no known monogenic disease, and further evaluate its relevance with immunological futures and clinical complications of patients. MethodsThe study population comprised patients with CVID, LRBA deficiency and age–sex matched healthy controls. Mutation analysis was done by whole exome sequencing in CVID patients to rule out monogenic PIDs. After CD4+ T cell stimulation with anti-CD3 and anti-CD28 monoclonal antibodies, gene expression of IL-4, IL-5, IL-10 and transcription factor GATA3 was evaluated by real-time polymerase chain reaction. The protein of mentioned cytokines was assessed by enzyme-linked immunosorbent assay. ResultsThe main clinical presentations of CVID patients were infections only and lymphoproliferations phenotypes, but in LRBA patients were autoimmune and enteropathy phenotype. The frequencies of CD4+ T cells were significantly reduced in LRBA and CVID patients. There were no statistically significant differences among GATA3, IL4, and IL5 gene expressions by CD4+ T cells of patients and controls, however, the IL10 expressions in CVID patients was significantly lower than in LRBA patients and HCs. As compared with HCs, CVID patients showed a prominent decrease in IL-4 and IL-10 production by CD4+ T cells. ConclusionsOur findings demonstrated that patients with CVID and LRBA deficiency (even with severe infectious and inflammatory complications) have not imbalance in Th2 response, which is in parallel with lower frequency of allergy and asthma in these patients.

A novel LPS-responsive beige-like anchor protein (LRBA) mutation presents with normal cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and overactive TH17 immunity

A novel LPS-responsive beige-like anchor protein (LRBA) mutation presents with normal cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and overactive TH17 immunity

Respiratory manifestations in LPS-responsive beige-like anchor (LRBA) protein-deficient patients.

Pulmonary manifestations are common in LRBA deficiency. Respiratory characteristics in LRBA-deficient patients should be investigated, monitored, and treated from the time of diagnosis. What is Known: • Lipopolysaccharide-responsive beige-like anchor (LRBA) deficiency is a syndrome of primary immune deficiency and immune dysregulation. • Studies concerning the pulmonary characteristics of LRBA-deficient patients are lacking. What is New: • Respiratory manifestations include infections, bronchiectasis, interstitial lung disease, thoracic lymphadenopathy, and clubbing. • Awareness to pulmonary morbidity in LRBA-deficient patients and involvement of a pulmonologist in the workup and clinical decision-making is important. • Respiratory characteristics in LRBA-deficient patients should be investigated, monitored, and treated from a young age.

Rapid Flow Cytometry-Based Test for the Diagnosis of Lipopolysaccharide Responsive Beige-Like Anchor (LRBA) Deficiency.

The diagnosis of lipopolysaccharide-responsive beige-like-anchor-protein (LRBA) deficiency currently relies on gene sequencing approaches that do not support a timely diagnosis and clinical management. We developed a rapid and sensitive test for clinical implementation based on the detection of LRBA protein by flow cytometry in peripheral blood cells after stimulation. LRBA protein was assessed in a prospective cohort of 54 healthy donors and 57 patients suspected of LRBA deficiency. Receiver operating characteristics analysis suggested an LRBA:MFI ratio cutoff point of 2.6 to identify LRBA-deficient patients by FACS with 94% sensitivity and 80% specificity and to discriminate them from patients with a similar clinical picture but other disease-causing mutations. This easy flow cytometry-based assay allows a fast screening of patients with suspicion of LRBA deficiency reducing therefore the number of patients requiring LRBA sequencing and accelerating the treatment implementation. Detection of biallelic mutations in LRBA is however required for a definitive diagnosis.

Precision medicine in the treatment of primary immunodeficiency diseases.

Since the 1990s with the advances in molecular biology, a number of genetic defects have been described. The International Union of Immunological Sciences has recently updated the classification of genetic defects associated with primary immune deficiencies that now number 354. With the ever-expanding list of new monogenic disorders and a better understanding of the immunobiology and function of these defective genes, new therapies have emerged particularly aimed at the autoimmune and inflammatory conditions that plague these patients. Immune deficiencies associated with gain-of-function (GOF) mutations are a potential category for targeted therapies to control the GOF activities of the mutated gene. In addition to the increased susceptibility to infections these patients have autoimmune and inflammatory diseases that are difficult to control with conventional therapies. The dysregulated immune functions of the activated phospholipase-3-kinase δ syndrome, cytotoxic T lymphocyte-associated antigen-4 haploinsufficiency, lipopolysaccharide-responsive beige-like anchor deficiency, the GOF mutations of signal transducer and activator of transcription 1 and 3 immune deficiencies will be reviewed. The targeted therapies for each of these immune deficiencies using small molecule kinase inhibitors and fusion protein biologic modifiers will be described. In this review, we explore the recent advances in precision medicine treatment of several primary immunodeficiency syndromes in which immune dysregulation is a key feature. Understanding the immunobiology associated with these GOF mutations has led to the use of biologic therapies to better control the associated autoimmune and inflammatory manifestations.

Identification of Variants in RET and IHH Pathway Members in a Large Family With History of Hirschsprung Disease

Hirschsprung disease (HSCR) is an inherited congenital disorder characterized by absence of enteric ganglia in the distal part of the gut. Variants in ret proto-oncogene (RET) have been associated with up to 50% of familial and 35% of sporadic cases. We searched for variants that affect disease risk in a large, multigenerational family with history of HSCR in a linkage region previously associated with the disease (4q31.3-q32.3) and exome wide. We performed exome sequencing analyses of a family in the Netherlands with 5 members diagnosed with HSCR and 2 members diagnosed with functional constipation. We initially focused on variants in genes located in 4q31.3-q32.3; however, we also performed an exome-wide analysis in which known HSCR or HSCR-associated gene variants predicted to be deleterious were prioritized for further analysis. Candidate genes were expressed in HEK293, COS-7, and Neuro-2a cells and analyzed by luciferase and immunoblot assays. Morpholinos were designed to target exons of candidate genes and injected into 1-cell stage zebrafish embryos. Embryos were allowed to develop and stained for enteric neurons. Within the linkage region, we identified 1 putative splice variant in the lipopolysaccharide responsive beige-like anchor protein gene (LRBA). Functional assays could not confirm its predicted effect on messenger RNA splicing or on expression of the mab-21 like 2 gene (MAB21L2), which is embedded in LRBA. Zebrafish that developed following injection of the lrba morpholino had a shortened body axis and subtle gut morphological defects, but no significant reduction in number of enteric neurons compared with controls. Outside the linkage region, members of 1 branch of the family carried a previously unidentified RET variant or an in-frame deletion in the glial cell line derived neurotrophic factor gene (GDNF), which encodes a ligand of RET. This deletion was located 6 base pairs before the last codon. We also found variants in the Indian hedgehog gene (IHH) and its mediator, the transcription factor GLI family zinc finger 3 (GLI3). When expressed in cells, the RET-P399L variant disrupted protein glycosylation and had altered phosphorylation following activation by GDNF. The deletion in GDNF prevented secretion of its gene product, reducing RET activation, and the IHH-Q51K variant reduced expression of the transcription factor GLI1. Injection of morpholinos that target ihhreduced the number of enteric neurons to 13% ± 1.4% of control zebrafish. In a study of a large family with history of HSCR, we identified variants in LRBA, RET, the gene encoding the RET ligand (GDNF), IHH, and a gene encoding a mediator of IHH signaling (GLI3). These variants altered functions of the gene products when expressed in cells and knockout of ihh reduced the number of enteric neurons in the zebrafish gut.

Polyautoimmunity in Patients with LPS-Responsive Beige-Like Anchor (LRBA) Deficiency

ABSTRACTBackground: Polyautoimmunity is defined as the presence of more than one autoimmune disorder in a single patient. Lipopolysaccharide (LPS)-responsive beige-like anchor (LRBA) deficiency is one of the monogenic causes of polyautoimmunity. The aim of this study was to report the characteristics of polyautoimmunity in patients with LRBA deficiency.Methods: A total of 14 LRBA deficiency patients with confirmed autoimmunity were enrolled in this study. For those patients with polyautoimmunity, demographic information, clinical records, laboratory, and molecular data were collected. We also compared our results with the currently reported patients with LRBA deficiency associated with polyautoimmunity.Results: In 64.2% (9 out of 14) of patients, autoimmunity presented as polyautoimmunity. In these patients, autoimmune cytopenias were the most frequent complication, observed in seven patients. Three patients presented with four different types of autoimmune conditions. The review of the literature showed that 41 of 72 reported LRBA deficient patients (74.5%) had also polyautoimmunity, with a wide spectrum of autoimmune diseases described. Hematopoietic stem cell transplantation is increasingly used as the treatment for patients with severe polyautoimmunity associated to LRBA deficiency.Conclusions: Mutation in LRBA gene is one of the causes of monogenic polyautoimmunity. Awareness of this association is important in order to make an early diagnosis and prompt treatment.

Primer İmmün Yetmezliklerde Akan Hücre Ölçer ile Hücre İçi Protein İfadesinin Tanısal Kullanımı; Marmara Deneyimi

Objective: The aim of our study was the optimization and standardization of intracellular dedicator of cytokinesis 8 (DOCK8), LPS-responsive beige-like anchor protein (LRBA), SH2D1A/SLAMassociated protein (SAP) and X-linked inhibitor of apoptosis protein (XIAP) protein expressions in healthy controls with a single flow cytometer protocol and to concomitantly evaluate the possible use of this method for diagnosis. Materials and Methods: Peripheral blood mononuclear cells were isolated from heparinized blood samples. Protein expressions were analyzed as mean fluorescein intensity difference (∆MFI) according to the isotype. Results: ∆MFI values obtained by DOCK8 antibody staining were 21.3±4 in CD3+ T cells and 25±3.3 in CD20+ T cells in healthy controls. These values in patients with DOCK8 deficiency were either very low or completely absent. ∆MFI values obtained by LRBA protein antibody staining were 36±7.7 in healthy controls, while they were at the very low levels of 5.9±1.8 in the LRBA protein deficiency patients. The values obtained by SAP and XIAP antibody staining were 30.2±3 in CD8+ T cells for SAP, 13.9±3.2 in CD3+ T and 14.6±3.5 in CD20+ B cells for XIAP. Since the SAP and XIAP results were not confirmed by gene sequencing, the results were not compared to healthy controls. Conclusion: Due to its rapid and reliable results in clinically relevant cases for DOCK8 and LRBA deficiencies, analysis of protein expression is primarily suitable to evaluate intracellular staining protocol by flow cytometer. In addition, this particular method could be suitable for patients considered to be SAP and XIAP deficient.

LRBA Eksikliği Tanısında Akan Hücre Ölçerde Protein İfadesi

Objective: Lipopolysaccharide-responsive beige-like anchor (LRBA) plays a role in cell surface expression of inhibitory cytotoxic T lymphocyte-associated protein-4 (CTLA-4) protein. Recently identified LRBA deficiency leads to immune deficiency and autoimmunity and is diagnosed by mutation analyses and protein expression. Herein, we quantified stimulated and unstimulated intracellular LRBA protein expression by flow cytometry in LRBA deficiency patients.Materials and Methods: Five LRBA deficient patients and seven healthy controls were evaluated. The LRBA expressions were assessed in peripheral-blood-mononuclear-cells in the presence or absence of phorbol-miristat-acetate and ionomycin stimulation. The difference in mean-fluorescence-intensity (ΔMFI) was calculated.Results: The differences in mean-fluorescence-intensity values of LRBA by flow cytometry were 24±9 for the healthy controls and 4.8±2.8 for the patients. ΔMFIs were 20.8 for P3, 19 for P4 and 49.6 for healthy controls with stimulants and 4.8, 4.6 and 20.1 respectively without stimulants.Conclusion: As a rapid and widely available assay, flow cytometric assessment of intracellular LRBA expression has been found to be an effective and reliable method in the identification of LRBA deficiency.

Modeling primary immune regulatory disorders: Ferrari or Yugo?

Despite about 75 million years of evolutionary separation, mice have proven to be remarkably informative for understanding the human immune system. Many immune signaling and developmental pathways are nearly identical between mouse and man, and some pathways, such as NK cell sensing of self, display clear evolutionary convergence. In this issue, Burnett et al. and Gamez-Diaz et al. independently describe the phenotype of Lipopolysaccharide Responsive Beige-like Anchor (LRBA) deficient mice. LRBA-deficient humans have a striking and severe syndrome of varied autoimmunity, lymphoproliferation, gut inflammation and immune deficiency.1 In contrast, these two groups report that LRBA-deficient mice are generally quite well. Despite aging and/or challenge with infectious organisms, these animals display none of the pathologies seen in humans. Of note, LRBA knockout mice have decreased CTLA4 protein levels, as is seen in LRBA-deficient patients, and is thought to underlie disease development. Both groups also noted other subtle immune abnormalities not correlated in patients to date: a decrease of the innate-like B1 B cells, and evidence of increased IgA production. These abnormalities are not predicted by any known function of LRBA, but may provide additional clues to disease pathogenesis.

Immunological phenotype of the murine Lrba knockout.

Biallelic mutations in the human lipopolysaccharide responsive beige-like anchor (LRBA) gene lead to a primary immunodeficiency known as LRBA deficiency, characterized by a broad range of clinical manifestations including autoimmunity, organomegaly, hypogammaglobulinemia and recurrent infections. Considering the phenotypic heterogeneity in patients and the severity of the disease, our aim was to assess the role of LRBA in immune cells and to understand the underlying pathomechanisms through the study of a Lrba knockout (Lrba-/-) mouse model. LRBA-deficient mice did not show severe clinical or immunological signs of disease, either at steady state under specific-pathogen-free conditions, after vaccination with T-dependent and T-independent antigens, or in the context of acute infections with lymphocytic choriomeningitis virus (LCMV) or Salmonella Typhimurium. Although Lrba-/- mice were able to produce normal serum immunoglobulin M (IgM) and IgG and to mount a specific immune response after immunization, they showed elevated serum and secretory basal IgA levels. LRBA was dispensable for B- and T-cell development, as well as for in vitro B-cell proliferation, survival, isotype switching and plasmablast differentiation. Interestingly, Lrba-/- mice displayed decreased cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) expression by regulatory T cells and activated conventional CD4+ and CD8+ T lymphocytes, reduced frequency of peritoneal B-1a cells along with diminished interleukin-10 production and increased percentages of T follicular helper cells in Peyer's patches, but without developing overt signs of autoimmunity. Our findings expand the role of LRBA in immune regulatory mechanisms previously reported in patients, and suggest a novel role in IgA production that is crucial for the protection of mucosal surfaces and gut-associated immune tolerance.

Murine LRBA deficiency causes CTLA-4 deficiency in Tregs without progression to immune dysregulation.

Inherited mutations in lipopolysaccharide-responsive beige-like anchor (LRBA) cause a recessive human immune dysregulation syndrome with memory B-cell and antibody deficiency (common variable immunodeficiency), inflammatory bowel disease, enlarged spleen and lymph nodes, accumulation of activated T cells and multiple autoimmune diseases. To understand the pathogenesis of the syndrome, C57BL/6 mice carrying a homozygous truncating mutation in Lrba were produced using CRISPR/Cas9-mediated gene targeting. These mice revealed that LRBA has a critical, cell-autonomous role in promoting cytotoxic T-lymphocyte antigen-4 (CTLA-4) accumulation within CD4 effector T cells and FOXP3+ T-regulatory cells (Tregs). In young mice, or in chimeric mice where only half of the T cells are LRBA deficient, low CTLA-4 was the only detectable abnormality in Tregs, whereas in old mice FOXP3 was also decreased. Low CTLA-4 did not translate into increased CD86 on B cells unless the LRBA-deficient mice were immunised, and neither immunisation nor chronic lymphocytic choriomeningitis virus infection precipitated immune dysregulation. LRBA deficiency did not alter antigen-specific B-cell activation, germinal centre (GC) formation, isotype switching or affinity maturation. Paradoxically, CD86 was decreased on GC B cells in LRBA-deficient mice, pointing to compensatory mechanisms for controlling CD86 in the face of low CTLA-4. These results add to the experimental rationale for treating LRBA deficiency with the CTLA4-Ig fusion protein, Abatacept, and pose questions about the limitations of laboratory experiments in mice to reproduce human disease in natura.

Clinical, immunologic, molecular analyses and outcomes of iranian patients with LRBA deficiency: A longitudinal study.

LPS-responsive beige-like anchor protein (LRBA) deficiency is a combined immunodeficiency caused by mutation in LRBA gene. The patients have a variety of clinical symptoms including hypogammaglobulinemia, recurrent infections, autoimmunity, and enteropathy. A total of 17 LRBA-deficient patients were enrolled in this longitudinal study. For all patients, demographic information, clinical records, laboratory, and molecular data were collected. Hypogammaglobulinemia was reported in 14 (82.4%), CD4+ T-cell deficiency in five (29.4%), NK cell deficiency in three (21.4%), and CD19+ B-cell deficiency in 11 (64.7%) patients. All patients had history of infectious complications; pneumonia was the most common (76.5%) occurring infection. A history of lymphoproliferative disorders was observed in 14 (82.3%), enteropathy in 13 (76.5%), allergic symptoms in six (35.5%), neurologic problems in four (23.5), and autoimmunity (mostly autoimmune cytopenia) in 13 (76.5%) patients. Sirolimus treatment improved enteropathy of patients with remarkable success. The 20-year overall survival rate declined to 70.6%. LRBA deficiency has a very broad and variable phenotype and should be considered, especially in children with early-onset hypogammaglobulinemia, severe autoimmune manifestations, enteropathy, lymphoproliferation, and recurrent respiratory tract infections.

Exaggerated follicular helper T-cell responses in patients with LRBA deficiency caused by failure of CTLA4-mediated regulation

LPS-responsive beige-like anchor protein (LRBA) and cytotoxic T lymphocyte-associated antigen 4 (CTLA4) deficiencies give rise to overlapping phenotypes of immune dysregulation and autoimmunity, with dramatically increased frequencies of circulating follicular helper T (cTFH) cells. We sought to determine the mechanisms of cTFH cell dysregulation in patients with LRBA deficiency and the utility of monitoring cTFH cells as a correlate of clinical response to CTLA4-Ig therapy. cTFH cells and other lymphocyte subpopulations were characterized. Functional analyses included invitro follicular helper T (TFH) cell differentiation and cTFH/naive B-cell cocultures. Serum soluble IL-2 receptor α chain levels and invitro immunoglobulin production by cultured B cells were quantified by using ELISA. cTFH cell frequencies in patients with LRBA or CTLA4 deficiency sharply decreased with CTLA4-Ig therapy in parallel with other markers of immune dysregulation, including soluble IL-2 receptor α chain, CD45RO+CD4+ effector T cells, and autoantibodies, and this was predictive of favorable clinical responses. cTFH cells in patients with LRBA deficiency were biased toward a TH1-like cell phenotype, which was partially reversed by CTLA4-Ig therapy. LRBA-sufficient but not LRBA-deficient regulatory T cells suppressed invitro TFH cell differentiation in a CTLA4-dependent manner. LRBA-deficient TFH cells supported invitro antibody production by naive LRBA-sufficient B cells. cTFH cell dysregulation in patients with LRBA deficiency reflects impaired control of TFH cell differentiation because of profoundly decreased CTLA4 expression on regulatory T cells and probably contributes to autoimmunity in patients with this disease. Serial monitoring of cTFH cell frequencies is highly useful in gauging the clinical response of LRBA-deficient patients to CTLA4-Ig therapy.

Treatment of severe forms of LPS-responsive beige-like anchor protein deficiency with allogeneic hematopoietic stem cell transplantation

Treatment of severe forms of LPS-responsive beige-like anchor protein deficiency with allogeneic hematopoietic stem cell transplantation

Consanguineous Siblings with a Novel Mutation in Lipopolysaccharide-Responsive Beige-like Anchor protein (LRBA)

Consanguineous Siblings with a Novel Mutation in Lipopolysaccharide-Responsive Beige-like Anchor protein (LRBA)

Treatment of Infantile Inflammatory Bowel Disease and Autoimmunity by Allogeneic Stem Cell Transplantation in LPS-Responsive Beige-Like Anchor Deficiency.

Inflammatory bowel disease (IBD) in young children can be a clinical manifestation of various primary immunodeficiency syndromes. Poor clinical outcome is associated with poor quality of life and high morbidity from the complications of prolonged immunosuppressive treatment and malabsorption. In 2012, mutations in the lipopolysaccharide-responsive beige-like anchor (LRBA) gene were identified as the cause of an autoimmunity and immunodeficiency syndrome. Since then, several LRBA-deficient patients have been reported with a broad spectrum of clinical manifestations without reliable predictive prognostic markers. Allogeneic hematopoietic stem cell transplantation (alloHSCT) has been performed in a few severely affected patients with complete or partial response. Herein, we present a detailed course of the disease and the transplantation procedure used in a LRBA-deficient patient suffering primarily from infantile IBD with immune enteropathy since the age of 6 weeks, and progressive autoimmunity with major complications following long-term immunosuppressive treatment. At 12 years of age, alloHSCT using bone marrow of a fully matched sibling donor—a healthy heterozygous LRBA mutant carrier—was performed after conditioning with a reduced-intensity regimen. During the 6-year follow-up, we observed a complete remission of enteropathy, autoimmunity, and skin vitiligo, with complete donor chimerism. The genetic diagnosis of LRBA deficiency was made post-alloHSCT by detection of two compound heterozygous mutations, using targeted sequencing of DNA samples extracted from peripheral blood before the transplantation.

The plethora, clinical manifestations and treatment options of autoimmunity in patients with primary immunodeficiency.

Although the association between primary immunodeficiency and autoimmunity is already well-known, it has once again become a topic of debate with the discovery of newly-defined immunodeficiencies. Thus, investigation of the mechanisms of development of autoimmunity in primary immunodefficiency and new target-specific therapeutic options has come to the fore. In this study, we aimed to examine the clinical findings of autoimmunity, autoimmunity varieties, and treatment responses in patients who were genetically diagnosed as having primary immunodeficiency. The files of patients with primary immunodeficiency who had clinical findings of autoimmunity, who were diagnosed genetically, and followed up in our clinic were investigated. The demographic and clinical features of the patients and their medical treatments were evaluated. Findings of autoimmunity were found in 30 patients whose genetic mutations were identified. The mean age at the time of the first symptoms was 8.96±14.64 months, and the mean age of receiving a genetic diagnosis was 82.55±84.71 months. The most common diseases showing findings of autoimmunity included immune dysregulation, polyendocrinopathy, enteropathy X-linked syndrome (16.7%); autoimmune lymphoproliferative syndrome (10%); lipopolysaccharide-responsive beige-like anchor protein deficiency (10%); and DiGeorge syndrome (10%). Twelve (40%) patients showed findings of autoimmunity at the time of first presentation. The most common findings of autoimmunity included inflammatory bowel disease, inflammatory bowel disease-like findings (n=14, 46.7%), immune thrombocytopenic purpura (n=11, 36.7%), and autoimmune hemolytic anemia (n=9, 30.0%). A response to immunosupressive agents was observed in 15 (50%) patients. Ten patients underwent hematopoietic stem cell transplantation. Six patients were lost to follow-up due to a variety of complications. Autoimmunity is frequently observed in patients with primary immunodeficiency. The possibility of primary immunodeficiency should be considered in patients with early-onset manifestations of autoimmunity, and these patients should be carefully monitored in terms of immunodeficiency development. Early diagnosis of primary immunodeficiency may provide favorable outcomes in terms of survival.

LRBA is Essential for Allogeneic Responses in Bone Marrow Transplantation.

The PH-BEACH-WD40 (PBW) protein family members play a role in coordinating receptor signaling and intracellular vesicle trafficking. LPS-Responsive-Beige-like Anchor (LRBA) is a PBW protein whose immune function remains elusive. Here we show that LRBA-null mice are viable, but exhibit compromised rejection of allogeneic, xenogeneic and missing self bone-marrow grafts. Further, we demonstrate that LRBA-null Natural Killer (NK) cells exhibit impaired signaling by the key NK activating receptors, NKp46 and NKG2D. However, induction of IFN-γ by cytokines remains intact, indicating LRBA selectively facilitates signals by receptors for ligands expressed on the surface of NK targets. Surprisingly, LRBA limits immunoregulatory cell numbers in tissues where GvHD is primed or initiated, and consistent with this LRBA-null mice also demonstrate resistance to lethal GvHD. These findings demonstrate that LRBA is redundant for host longevity while being essential for both host and donor-mediated immune responses and thus represents a unique and novel molecular target in transplant immunology.