CD40 Deficiency Research Articles

Clinical and immunological features of four patients with activation-induced cytidine deaminase deficiency: Renal amyloidosis and other presentations.

Activation-induced cytidine deaminase (AID) deficiency is a rare autosomal recessive inborn error of immunity (IEI) characterized by increased susceptibility to infections, autoimmunity, and/or autoinflammation. AID plays an important role in immunoglobulin class switching and somatic hypermutation. AID deficiency patients have very low or absent levels of IgG, IgA, and IgE, while IgM level is elevated. The disease is designated as type 2 hyperimmunoglobulin M syndrome (HIGM-2). To date, around 130 patients with HIGM-2 have been reported, none from Egypt. Four patients from three different consanguineous families with elevated serum IgM and low IgG and IgA were included in the study. After the exclusion of CD40 and/or CD40L deficiency by flow cytometry, patients' samples were tested by a panel covering 452 genes (four bases PID-Pro) on the Illumina Miseq platform. All patients suffered repeated infections since childhood. Patients 1-3 had inflammatory bowel disease-like (IBD-like) symptoms, while patient 4 did not have autoimmune manifestations. Patient 1 is the first HIGM-2 patient to be reported to have renal amyloidosis as part of the autoinflammation. Patients 1-3 had the same pathogenic variant (NM_020661.4 (AID):c.406del, p.Ile136Ter), while patient 4 had another pathogenic variant (NM_020661.4 (AID):c.374G>A, p.Gly125Glu). The variant p.Ile136Ter was not reported before in any of the documented HIGM-2 patients. HIGM-2 is a rare IEI that can be overlooked; hence, patients' diagnosis is delayed. Autoimmune and autoinflammatory manifestations develop later in the disease course leading to significant morbidities. The diagnosis can be suspected after exclusion of CD40/CD40L deficiencies by flow cytometry, and the diagnosis can be confirmed by genetic testing.

Abstract 106: Cd40 Is Required For B1b Cell Homeostasis In Atherosclerosis

The CD40-CD40L co-stimulatory dyad has been identified as critical player in atherosclerosis. Our previous work has shown that CD40 and CD40L have cell divergent effects on atherosclerosis. Deficiency of the CD40-CD40L dendritic cell-T cell axis decreased atherosclerosis via reducing T helper 1 responses, whereas deficiency of macrophages CD40 reduced atherosclerosis by enhancing efferocytosis and reducing necrotic core content. CD40 is highly expressed on B cells and interacts with CD40L on T cells to induce antibody production and T follicular helper cell responses. We therefore hypothesize that deletion of CD40 will reduce atherosclerosis. We aim to unravel the role of B cell CD40 in atherosclerosis. CD40 expression on B cell subsets was determined on peripheral blood mononuclear cells of patients and correlated with severity of coronary artery disease (CAD). Atherosclerosis was analyzed in CD19 Cre CD40 flfl ApoE -/- mice that were fed an atherogenic diet for 14 weeks. Patients with CAD showed a decrease in CD40 on their putative B1 cells, which was associated with increased plaque burden and decreased plaque fibrosis as detected by coronary intravascular ultrasound. Depletion of CD40 on B cells in ApoE -/- mice resulted in a decreased germinal center formation and inadequate IgM production as expected. However, in line with our patient data, absence of B cell-CD40 increased atherosclerosis. This was caused by a reduction in B1 cells and consequently a reduction in atheroprotective anti-oxidation specific epitope (OSE) IgMs. Transfer of CD40-competent B1b cells in B cell-CD40-deficient mice restored anti-OSE IgM levels and prevented the increase in atherosclerosis. CD40-deficient B1b cells have an altered mTOR signaling pathway, impaired mitochondrial function, excessive uptake of lipids, increased cellular stress and accelerated cell death. Data indicate that CD40-deficiency promotes phosphorylation of RAPTOR and protein kinase B (AKT). We have identified a novel function of CD40 on B1b cells. B1b cell-CD40 exerts an anti-atherogenic role by regulating B1b cell metabolic homeostasis via mTOR pathway. Further mechanistic insights into how CD40 mounts adequate atheroprotective anti-OSE IgM production are currently being investigated.

Dual novel variants in CD40 leading to hyper IgM syndrome: a case report of a school-aged female with new-onset recurrent pneumonia

Introduction: Hyper IgM (HIGM) syndrome is an inborn error of immunity (IEI) that occurs due to defects in immunoglobulin class switch recombination (Ig-CSR). HIGM syndrome typically presents with recurrent infections in early childhood, and is often characterized on investigation with decreased IgG, IgA, and IgE titres, alongside normal or elevated IgM. A common cause of HIGM syndrome is a disruption to the CD40-CD40 ligand (CD40L) interaction that triggers Ig-CSR, of which variants in CD40 are much rarer than those in CD40L. We present a case of an 11-year-old female with HIGM syndrome caused by two novel variants of in the CD40 gene. Aim: To describe a case report of an eleven-year-old female with HIGM syndrome presenting with recurrent pneumonia. Methods: Data was collected retrospectively from the patient’s medical records. Laboratory investigations included quantitative immunoglobulins, quantitative B and T cell subsets, genetic testing using a primary immunodeficiency panel, and a functional assay for CD40 expression. Results: The proband is an 11-year-old female, who presented with recurrent pneumonia, otitis, and septic arthritis. Investigations revealed neutropenia, low IgA, elevated IgM and normal IgG, along with absent vaccine responses. She was identified to harbour two novel variants in CD40: an intronic variant c.52-13A>G p.(?) and a missense variant c.466T>C p.(Ser156Pro). Functional assay indicated low expression of CD40 compared to healthy control, confirming the diagnosis of CD40 deficiency. Conclusion: Class switch defects, such as CD40 deficiency, are rare but significant diagnoses within the spectrum of IEI. This case demonstrates that despite the absence of some clinical red flags for immunodeficiency in infancy, IEIs remain an important consideration in pediatric patients regardless of age. Increasing clinical awareness of IEI will lead to earlier diagnoses, initiation of appropriate treatment, and prevention of potential complications. Statement of novelty: We describe a patient with a late presentation of hyper IgM syndrome due to two novel variants in the CD40 gene, thus expanding the spectrum of CD40 gene variants.

Differential induction of donor-reactive Foxp3+ regulatory T cell via blockade of CD154 vs CD40

Recently published studies in both murine models and a meta-analysis of non-human primate renal transplant studies showed that anti-CD154 reagents conferred a significant survival advantage over CD40 blockers in both animal models and across multiple organs. Here we sought to compare the induction of donor-reactive forkhead box P3+-induced regulatory T cells (Foxp3+ iTreg) in mice treated with anti-CD154 versus anti-CD40 monoclonal antibodies (mAbs). Results indicated that while treatment with anti-CD154 mAb resulted in a significant increase in the frequency of donor-reactive CD4+ Foxp3+ iTreg following transplantation, treatment with anti-CD40 or Cd40 deficiency failed to recapitulate this result. Because we recently identified CD11b as an alternate receptor for CD154 during alloimmunity, we interrogated the role of CD154:CD11b interactions in the generation of Foxp3+ iTreg and found that blockade of CD11b in Cd40−/− recipients resulted in increased donor-reactive Foxp3+ iTreg as compared with CD40 deficiency alone. Mechanistically, CD154:CD11b inhibition decreased interleukin (IL)-1β from CD11b+ and CD11c+ dendritic cells, and blockade of IL-1β synergized with CD40 deficiency to promote Foxp3+ iTreg induction and prolong allograft survival. Taken together, these data provide a mechanistic basis for the observed inferiority of anti-CD40 blockers as compared with anti-CD154 mAb and illuminate an IL-1β-dependent mechanism by which CD154:CD11b interactions prevent the generation of donor-reactive Foxp3+ iTreg during transplantation.

CD40 deficiency attenuates neuroinflammation in experimental epilepsy

CD40 deficiency attenuates neuroinflammation in experimental epilepsy

Profiling B-cell Response: Hyperimmunoglobulin M Syndrome due to CD40 Deficiency

Hyperimmunoglobulin M (IgM) Type 3 (HIGM 3) syndromes are rare autosomal recessive disorders characterized by intrinsic B-cell defects that restricts immunoglobulin class usage. HIGM 3 due to the absence of CD40 on B-cells is incredibly rare and remains poorly characterized. We describe the B-cell profile of a 6-year-old patient with a previously uncharacterized homozygous mutation in TNFRSF5 (CD40).

Adipocytes control hematopoiesis and inflammation through CD40 signaling.

The co-stimulatory CD40-CD40L dyad plays an important role in chronic inflammatory diseases associated with aging. Although CD40 is mainly expressed by immune cells, CD40 is also present on adipocytes. We aimed to delineate the role of adipocyte CD40 in the aging hematopoietic system and evaluated the effects of adipocyte CD40 deficiency on cardiometabolic diseases. Adult adipocyte CD40-deficient mice (AdiCD40KO) mice had a decrease in bone marrow hematopoietic stem cells (Lin-Sca+cKit+, LSK) and common lymphoid progenitors, which was associated with increased bone marrow adiposity and T-cell activation, along with elevated plasma corticosterone levels, a phenotype that became more pronounced with age. Atherosclerotic AdiCD40koApoE-/- (CD40AKO) mice also displayed changes in the LSK population, showing increased myeloid and lymphoid multipotent progenitors, and augmented corticosterone levels. Increased T-cell activation could be observed in bone marrow, spleen, and adipose tissue, while the numbers of B cells were decreased. Although atherosclerosis was reduced in CD40AKO mice, plaques contained more activated T cells and larger necrotic cores. Analysis of peripheral adipose tissue in a diet-induced model of obesity revealed that obese AdiCD40KO mice had increased T-cell activation in adipose tissue and lymphoid organs, but decreased weight gain and improved insulin sensitivity, along with increased fat oxidation. In conclusion, adipocyte CD40 plays an important role in maintaining immune cell homeostasis in bone marrow during aging and chronic inflammatory diseases, particularly of the lymphoid populations. Although adipocyte CD40 deficiency reduces atherosclerosis burden and ameliorates diet-induced obesity, the accompanying T-cell activation may eventually aggravate cardiometabolic diseases.

A single-center study points to diverse features and outcome in patients with Hyperimmunoglobulin M Syndrome and Class- Switch Recombination defects.

Isotype class-switch recombination (CSR), somatic hypermutation (SHM), B cell signalling and DNA repair mechanisms defects are responsible for high IgM. The hyperimmunoglobulin M (HIGM) phenotype and CSR-related defects are now classified under primary antibody defects, combined immunodeficiencies or syndromic immunodeficiencies groups. The aim of the study is to evaluate the diverse phenotypic/genotypic/laboratory characteristics and outcome of patients with CSR defects and HIGM-related defects. We enrolled 50 patients. The most common gene defect was Activation-induced cytidine deaminase (AID) deficiency (n=18), followed by CD40 Ligand (CD40L) (n=14) and CD40 (n=3) deficiency. Median ages at first symptom and diagnosis were significantly lower in CD40L deficiency (8.5 and 30 months, respectively) than AID deficiency (30 and 114 months, respectively) (p=.001 and p=.008, respectively). Frequent clinical symptoms were recurrent (66%) and severe (14.9%) infections, and/or autoimmune/non-infectious inflammatory features (48.4%). Eosinophilia and neutropenia were at a higher rate in CD40L deficiency patients (77.8%, p=.002 and 77.8%, p=.002, respectively) when compared to AID deficiency. Median serum IgM level was low in 28.6% of CD40L deficiency patients. It was significantly lower when compared to AID deficiency (p < 0.001). Six patients (CD40L deficiency n=4, CD40 deficiency n=2) underwent hematopoietic stem cell transplantation. Five were alive at the last visit. Four patients two patients with CD40L deficiency, one with CD40 deficiency and one with AID deficiency had novel mutations. In conclusion; patients with CSR defects and HIGM phenotype may present with a wide range of clinical manifestations and laboratory findings. Low IgM, neutropenia and eosinophilia were prominent in patients with CD40L deficiency. Characterization of genetic defect-specific clinical and laboratory features may ease the diagnosis, prevent the underdiagnoses of patients and ameliorate the outcome.

Endothelial cell specific deficiency of CD40 stabilizes murine atherosclerotic lesions by impairing inflammatory cell recruitment

Background and Aims : Phenotypes of atherosclerotic plaques that favor plaque instability, subsequent rupture, and acute cardiovascular complications are driven by local inflammation of the vessel wall. The co-stimulatory CD40L–CD40 dyad exerts a critical role in atherosclerosis. The cell-type specific contribution of both molecules, however, remains elusive. Here, we evaluated the contribution of CD40 expressed on endothelial cells (ECs) in a mouse model of atherosclerosis.

Myeloid CD40 deficiency reduces atherosclerosis by impairing macrophages' transition into a pro-inflammatory state.

CD40 and its ligand, CD40L, play a critical role in driving atherosclerotic plaque development. Disrupted CD40-signalling reduces experimental atherosclerosis and induces a favourable stable plaque phenotype. We recently showed that small molecule-based inhibition of CD40-tumour necrosis factor receptor associated factor-6 interactions attenuates atherosclerosis in hyperlipidaemic mice via macrophage-driven mechanisms. The present study aims to detail the function of myeloid CD40 in atherosclerosis using myeloid-specific CD40-deficient mice. Cd40flox/flox and LysM-cre Cd40flox/flox mice on an Apoe-/- background were generated (CD40wt and CD40mac-/-, respectively). Atherosclerotic lesion size, as well as plaque macrophage content, was reduced in CD40mac-/- compared to CD40wt mice, and their plaques displayed a reduction in necrotic core size. Transcriptomics analysis of the CD40mac-/- atherosclerotic aorta revealed downregulated pathways of immune pathways and inflammatory responses. Loss of CD40 in macrophages changed the representation of aortic macrophage subsets. Mass cytometry analysis revealed a higher content of a subset of alternative or resident-like CD206+CD209b- macrophages in the atherosclerotic aorta of CD40mac-/- compared to CD40wt mice. RNA-sequencing of bone marrow-derived macrophages of CD40mac-/- mice demonstrated upregulation of genes associated with alternatively activated macrophages (including Folr2, Thbs1, Sdc1, and Tns1). We here show that absence of CD40 signalling in myeloid cells reduces atherosclerosis and limits systemic inflammation by preventing a shift in macrophage polarization towards pro-inflammatory states. Our study confirms the merit of macrophage-targeted inhibition of CD40 as a valuable therapeutic strategy to combat atherosclerosis.

Deficiency of Endothelial CD40 Induces a Stable Plaque Phenotype and Limits Inflammatory Cell Recruitment to Atherosclerotic Lesions in Mice.

The co-stimulatory CD40L-CD40 dyad exerts a critical role in atherosclerosis by modulating leukocyte accumulation into developing atherosclerotic plaques. The requirement for cell-type specific expression of both molecules, however, remains elusive. Here, we evaluate the contribution of CD40 expressed on endothelial cells (ECs) in a mouse model of atherosclerosis. Atherosclerotic plaques of apolipoprotein E-deficient (Apoe -/- ) mice and humans displayed increased expression of CD40 on ECs compared with controls. To interrogate the role of CD40 on ECs in atherosclerosis, we induced EC-specific (BmxCreERT2-driven) deficiency of CD40 in Apoe -/- mice. After feeding a chow diet for 25 weeks, EC-specific deletion of CD40 (iEC-CD40) ameliorated plaque lipid deposition and lesional macrophage accumulation but increased intimal smooth muscle cell and collagen content, while atherosclerotic lesion size did not change. Leukocyte adhesion to the vessel wall was impaired in iEC-CD40-deficient mice as demonstrated by intravital microscopy. In accord, expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) in the vascular endothelium declined after deletion of CD40. In vitro, antibody-mediated inhibition of human endothelial CD40 significantly abated monocyte adhesion on ECs. Endothelial deficiency of CD40 in mice promotes structural features associated with a stable plaque phenotype in humans and decreases leukocyte adhesion. These results suggest that endothelial-expressed CD40 contributes to inflammatory cell migration and consecutive plaque formation in atherogenesis.

Cryptococcal Meningoencephalitis in a Patient with Hyper IgM Syndrome Due to CD40 Deficiency: Case Report and Literature Review

Hyper-IgM syndrome (HIGM) due to CD40 deficiency is a very rare form of combined immunodeficiency with increased susceptibility to opportunistic infections. Cryptococcus is an opportunistic infection usually affecting immunocompromised individuals. This is the first report to describe a patient with HIGM due to CD40 deficiency presenting with meningoencephalitis secondary to Cryptococcus infection.

Macrophage CD40 plays a minor role in obesity-induced metabolic dysfunction.

Obesity is a low-grade inflammatory disease that increases the risk for metabolic disorders. CD40-CD40L signaling plays a central role in obesity-induced inflammation. Genetic deficiency of CD40L in diet-induced obesity (DIO) ameliorates adipose tissue inflammation, hepatic steatosis and increases insulin sensitivity. Unexpectedly, absence of CD40 worsened insulin resistance and caused excessive adipose tissue inflammation and hepatosteatosis. To investigate whether deficiency of macrophage CD40 is responsible for the phenotype observed in the CD40-/- mice, we generated CD40flflLysMcre and fed them a standard (SFD) and 54% high fat obesogenic diet (HFD) for 13 weeks. No differences in body weight, adipose tissue weight, adipocyte size, plasma cholesterol or triglyceride levels could be observed between CD40flflLysMcre and wild type (WT) mice. CD40flflLysMcre displayed no changes in glucose tolerance or insulin resistance, but had higher plasma adiponectin levels when fed a SFD. Liver weights, liver cholesterol and triglyceride levels, as well as the degree of hepatosteatosis were not affected by absence of macrophage CD40. CD40flflLysMcre mice displayed a minor increase in adipose tissue leukocyte infiltration on SFD and HFD, which did not result in differences in adipose tissue cytokine levels. We here show that loss of macrophage CD40 signaling does not affect obesity induced metabolic dysregulation and indicates that CD40-deficiency on other cell-types than the macrophage is responsible for the metabolic dysregulation, adipose tissue inflammation and hepatosteatosis that are observed in CD40-/- mice.

Haematopoietic stem cell transplant for hyper-IgM syndrome due to CD40 defects: a single-centre experience

Hyper-IgM syndrome due to CD40 deficiency (HIGM3) is a rare disease with only a few reported cases of haematopoietic stem cell transplantation (HSCT). In retrospective study, we reviewed all patients with HIGM3 who underwent HSCT at King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia, between 2008 and 2013. Six patients were identified. Three male and three female patients from three families. The median age of diagnosis was 13 months (range, 1-28 months). All lacked CD40 expression on B cells by flow cytometry. The median time from diagnosis to transplantation was 8.5 months (range, 1-17 months). For all patients, the donors were HLA-identical siblings, with the exception of one patient for whom the donor was a sibling with one antigen mismatch. The conditioning regimen was busulfan and cyclophosphamide in five patients and busulfan, cyclophosphamide and antithymocyte globulin in one patient. For GVHD prophylaxis, cyclosporine and methotrexate was used. All patients engrafted. The survival rate was 100%, with a median follow-up of 54 months (range, 30-116 months). One patient developed acute GVHD. All patients showed complete immune recovery with positive CD40 expression on B cells and discontinued IVIG replacement. Our study shows that HSCT is potentially effective at curing the disease.

CD40 deficiency in smooth muscle cells ameliorates atherogenesis and promotes a stable plaque phenotype in the aortic root

CD40 deficiency in smooth muscle cells ameliorates atherogenesis and promotes a stable plaque phenotype in the aortic root

CD40 DEFICIENCY: A UNIQUE ADULT PATIENT WITH HYPER IMMUNOGLOBULIN M SYNDROME AND NORMAL EXPRESSION OF CD40

Background: CD40 deficiency is an autosomal recessive, combined primary immunodeficiency characterized by defects of immunoglobulin class switch recombination and somatic hypermutation. It is part of an expanding group of diseases collectively known as hyper immunoglobulin M syndromes. Clinical manifestations of the disease usually begin early in life with recurrent sinopulmonary bacterial infections and susceptibility to opportunistic organisms. Only 16 patients from 12 unrelated families have been reported to date, all with lack of membrane expression of CD40 molecule. Methods: Prospective and retrospective data was collected from the patient’s medical records, and Sanger sequencing, flow cytometry analysis, real-time polymerase chain reaction and western blotting were performed. Results: In contrast with the patients reported previously, our patient’s mutation permits CD40 expression on the cell membrane and adds 37 amino acids to the cytoplasmic domain of the protein. We predict this change to affect 1 of the 2 known TRAF2 binding sites, as well as generate defective internalization of the receptor, both of which are required processes for functional signaling by CD40. Conclusion: Our patient’s unique phenotype is an opportunity to further understand the biology and function of the CD40 receptor. As illustrated by this case, relying solely on flow cytometry for diagnosis of CD40 deficiency has the potential of overlooking patients with mutations that may allow residual protein expression. Therefore, confirmatory mutation analysis should always be performed. Statement of novelty: We report on a patient with a novel mutation in CD40 and a unique phenotype, characterized by a complete lack of CD40 function despite normal protein expression. To our knowledge, this has not been reported previously. The patient has a milder phenotype than described for other patients with CD40 deficiency.

CD40 in Retinal Müller Cells Induces P2X7-Dependent Cytokine Expression in Macrophages/Microglia in Diabetic Mice and Development of Early Experimental Diabetic Retinopathy.

Müller cells and macrophages/microglia are likely important for the development of diabetic retinopathy; however, the interplay between these cells in this disease is not well understood. An inflammatory process is linked to the onset of experimental diabetic retinopathy. CD40 deficiency impairs this process and prevents diabetic retinopathy. Using mice with CD40 expression restricted to Müller cells, we identified a mechanism by which Müller cells trigger proinflammatory cytokine expression in myeloid cells. During diabetes, mice with CD40 expressed in Müller cells upregulated retinal tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), intracellular adhesion molecule 1 (ICAM-1), and nitric oxide synthase (NOS2), developed leukostasis and capillary degeneration. However, CD40 did not cause TNF-α or IL-1β secretion in Müller cells. TNF-α was not detected in Müller cells from diabetic mice with CD40+ Müller cells. Rather, TNF-α was upregulated in macrophages/microglia. CD40 ligation in Müller cells triggered phospholipase C–dependent ATP release that caused P2X7-dependent production of TNF-α and IL-1β by macrophages. P2X7−/− mice and mice treated with a P2X7 inhibitor were protected from diabetes-induced TNF-α, IL-1β, ICAM-1, and NOS2 upregulation. Our studies indicate that CD40 in Müller cells is sufficient to upregulate retinal inflammatory markers and appears to promote experimental diabetic retinopathy and that Müller cells orchestrate inflammatory responses in myeloid cells through a CD40-ATP-P2X7 pathway.

Primary immunodeficiencies associated with eosinophilia.

BackgroundEosinophilia is not an uncommon clinical finding. However, diagnosis of its cause can be a dilemma once common culprits, namely infection, allergy and reactive causes are excluded. Primary immunodeficiency disorders (PID) are among known differentials of eosinophilia. However, the list of PIDs typically reported with eosinophilia is small and the literature lacks an inclusive list of PIDs which have been reported with eosinophilia. This motivated us to review the literature for all PIDs which have been described to have elevated eosinophils as this may contribute to an earlier diagnosis of PID and further the understanding of eosinophilia.MethodsA retrospective PubMed, and Google Scholar search using the terms “eosinophilia” and “every individual PID” as classified by Expert Committee of the International Union of Immunological Societies with the limit of the English language was performed. Results were assessed to capture case(s) which reported eosinophilia in the context of PID conditions. Absolute eosinophil counts (AEC) were retrieved from manuscripts whenever reported.ResultsIn addition to the typical PID conditions described with eosinophilia, we document that MHC class II deficiency, CD3γ deficiency, STAT1 deficiency (AD form), Kostmann disease, cyclic neutropenia, TCRα deficiency, Papillon-Lefevre syndrome, CD40 deficiency, CD40L deficiency, anhidrotic ectodermal dysplasia with immune deficiency, ataxia-telangiectasia, common variable immunodeficiency disorders (CVID), Blau syndrome, CARD9 deficiency, neonatal onset multisystem inflammatory disease or chronic infantile neurologic cutaneous and articular syndrome (NOMID/CINCA), chronic granulomatous disease, MALT1 deficiency and Roifman syndrome have been noted to have elevated eosinophils. Severe eosinophilia (>5.0 × 109/L) was reported in Omenn syndrome, Wiskott Aldrich syndrome, ADA deficiency, autoimmune lymphoproliferative syndrome, immunodysregulation polyendocrinopathy enteropathy X-linked, STAT3 deficiency, DOCK8 deficiency, CD40 deficiency, MHC II deficiency, Kostmann disease, Papillon-Lefevre syndrome, and CVID.ConclusionsThis literature review shows that there is an extensive list of PIDs which have been reported with eosinophilia. This list helps clinicians to consider an extended differential diagnoses when tasked with exclusion of PID as a cause for eosinophilia.Electronic supplementary materialThe online version of this article (doi:10.1186/s13223-016-0130-4) contains supplementary material, which is available to authorized users.

Novel and recurrent AID mutations underlie prevalent autosomal recessive form of HIGM in consanguineous patients.

Immunoglobulin class switch recombination deficiencies (Ig-CSR-D) are characterized by normal or elevated serum IgM level and absence of IgG, IgA, and IgE. Most reported cases are due to X-linked CD40L deficiency. Activation-induced cytidine deaminase deficiency is the most frequent autosomal recessive form, whereas CD40 deficiency is more rare. Herein, we present the first North African study on hyper IgM (HIGM) syndrome including 16 Tunisian patients. Phenotypic and genetic studies allowed us to determine their molecular basis. Three CD40LG mutations have been identified including two novels (c.348_351dup and c.782_*2del) and one already reported mutation (g.6182G>A). No mutation has been found in another patient despite the lack of CD40L expression. Interestingly, three AICDA mutations have been identified in 11 patients. Two mutations were novel (c.91T>C and c.389A>C found in one and five patients respectively), and one previously reported splicing mutation (c.156+1T>G) was found in five patients. Only one CD40-deficient patient, bearing a novel mutation (c.109T>G), has been identified. Thus, unlike previous reports, AID deficiency is the most frequent underlying molecular basis (68%) of Ig-CSR-D in Tunisian patients. This finding and the presence of specific recurrent mutations are probably due to the critical role played by inbreeding in North African populations.

Deficiency of CD40 Reveals an Important Role for LIGHT in Anti-Leishmania Immunity.

We previously showed that LIGHT and its receptor herpes virus entry mediator (HVEM) are important for development of optimal CD4(+) Th1 cell immunity and resistance to primary Leishmania major infection in mice. In this study, we further characterized the contributions of this molecule in dendritic cell (DC) maturation, initiation, and maintenance of primary immunity and secondary anti-Leishmania immunity. Flow-cytometric studies showed that CD8α(+) DC subset was mostly affected by HVEM-Ig and lymphotoxin β receptor-Ig treatment. LIGHT signaling is required at both the priming and the maintenance stages of primary anti-Leishmania immunity but is completely dispensable during secondary immunity in wild type mice. However, LIGHT blockade led to impaired IL-12 and IFN-γ responses and loss of resistance in healed CD40-deficient mice after L. major challenge. The protective effect of LIGHT was mediated primarily via its interaction with lymphotoxin β receptor on CD8α(+) DCs. Collectively, our results show that although LIGHT is critical for maintenance of primary Th1 response, it is dispensable during secondary anti-Leishmania immunity in the presence of functional CD40 signaling as seen in wild type mice.