Autoimmune Lymphoproliferative Disease Research Articles

Monoallelic KRAS (G13C) mutation triggers dysregulated expansion in induced pluripotent stem cell-derived hematopoietic progenitor cells.

Although oncogenic RAS mutants are thought to exert mutagenic effects upon blood cells, it remains uncertain how a single oncogenic RAS impacts non-transformed multipotent hematopoietic stem or progenitor cells (HPCs). Such potential pre-malignant status may characterize HPCs in patients with RAS-associated autoimmune lymphoproliferative syndrome-like disease (RALD). This study sought to elucidate the biological and molecular alterations in human HPCs carrying monoallelic mutant KRAS (G13C) with no other oncogene mutations. We utilized induced pluripotent stem cells (iPSCs) derived from two unrelated RALD patients. Isogenic HPC pairs harboring either wild-type KRAS or monoallelic KRAS (G13C) alone obtained following differentiation enabled reliable comparative analyses. The compound screening was conducted with an established platform using KRAS (G13C) iPSCs and differentiated HPCs. Cell culture assays revealed that monoallelic KRAS (G13C) impacted both myeloid differentiation and expansion characteristics of iPSC-derived HPCs. Comprehensive RNA-sequencing analysis depicted close clustering of HPC samples within the isogenic group, warranting that comparative studies should be performed within the same genetic background. When compared with no stimulation, iPSC-derived KRAS (G13C)-HPCs showed marked similarity with the wild-type isogenic control in transcriptomic profiles. After stimulation with cytokines, however, KRAS (G13C)-HPCs exhibited obvious aberrant cell-cycle and apoptosis responses, compatible with "dysregulated expansion," demonstrated by molecular and biological assessment. Increased BCL-xL expression was identified amongst other molecular changes unique to mutant HPCs. With screening platforms established for therapeutic intervention, we observed selective activity against KRAS (G13C)-HPC expansion in several candidate compounds, most notably in a MEK- and a BCL-2/BCL-xL-inhibitor. These two compounds demonstrated selective inhibitory effects on KRAS (G13C)-HPCs even with primary patient samples when combined. Our findings indicate that a monoallelic oncogenic KRAS can confer dysregulated expansion characteristics to non-transformed HPCs, which may constitute a pathological condition in RALD hematopoiesis. The use of iPSC-based screening platforms will lead to discovering treatments that enable selective inhibition of RAS-mutated HPC clones.

Trombocitopenia primária imune com púrpura palpável: um relato de caso

Immune thrombocytopenia is a relatively common bleeding disorder characterized by isolated destruction of platelets by autoantibodies, with a typically acute onset, benign course and self-limiting in most cases. The aim of this report is to present a rare case of Primary Immune Thrombocytopenia (ITP) with palpable purpura, an uncommon manifestation in this disease and little described in the literature. This is a 12-year-old female adolescent who presented with palpable purpura, ecchymosis and oral cavity bleeding associated with thrombocytopenia and anemia. Initial investigation excluded autoimmune diseases, vasculitis, lymphoproliferative diseases and coagulation disorders, in addition to the myelogram showing typical findings of ITP: hypercellular bone marrow with megakaryocytic hyperplasia and decreased thrombocytogenesis. Due to the diversity of clinical presentation and the possibility of atypical manifestations, the diagnosis is often challenging, as in the case of this patient in which the main finding on physical examination was the presence of palpable purpura.

An investigation on the nutritional status and support of in-patients with common variable immunodeficiency

The study aimed to reveal for the first time the clinical characteristics, nutritional and metabolic status and support of hospitalized patients with common variant immunodeficiency disease (CVID), and provide reference to improve the long-term nutritional management for such patients. This is a retrospective cross-sectional study. Through searching the electronic medical record system of Peking Union Medical College Hospital, the study included 33 consecutive in-patients with CVID diagnosed in Jan 2016 to Jun 2021, with the male to female ratio of 16∶17. All their medical data, nutritional assessment and intervention retrospectively summarized and analyzed. Data with normal distribution were described using (x¯±s), and analyzed with independent sample t-test. Data with non-normal distribution were compared with non-parametric test. The results showed that the median onset-age of the included patients was 22 (10.0,36.5) years old, and the median duration was 9.0 (2.0,16.0) years. All patients had recurrent infections involving various systems (33/33), with development of autoimmune diseases (8/33) and lymphoproliferative disease or malignancy (9/33) in some cases among them. The nutritional risk screening 2002 (NRS 2002) scores revealed that 85.19% of adults had an NRS 2002≥3 points, and 33.33% of children had a BMI-for-age z score<-2. Weight loss occurred in 66.67% of patients (22/33), while 87.88% (29/33), 69.70% (23/33) and 81.82% (27/33) of patients respectively had anemia, hypoalbuminemia and decreased prealbumin. Among 22 patients with micronutrients status evaluated, 77.27% (17/22), 22.73% (5/22) and 31.82% (7/22) of patients respectively had lowered serum iron, folate deficiency and vitamin B12 insufficiency. Six patients underwent 25-OH-VD3 measurement, and were all testified to have vitamin D deficiency. Among all patients with nutritional risk, 56.00% of them underwent nutritional support: oral nutritional supplements (14 cases), enteral feeding (4 cases) and parenteral nutrition (5 cases). In conclusion, the condition of malnutrition was prevalent in patients with CVID, but was under-recognized and undertreated to some degree.

Thrombophilia Screening in Autoimmune Hemolytic Anemia: A Single-Center Cross-Sectional Study

Background Autoimmune hemolytic anemia (AIHA) is characterized by an increased rate of thrombosis, whose predictors are not completely clarified, although an association with active hemolysis (i.e., LDH &amp;gt;1.5 x ULN), anemia severity and previous splenectomy has been reported. Moreover, antithrombotic prophylaxis and its duration are not standardized in this patient-population. The value of thrombophilia screening, including congenital and acquired abnormalities, has not been established yet. Aim To investigate the prevalence of inherited and acquired thrombophilia abnormalities in a cohort of AIHA patients with or without thrombosis. Methods AIHA patients followed from January 2019 until September 2022 at a tertiary hematologic center in Milan, have been systematically tested for Factor V Leiden (FVL) and prothrombin (FII) G20210A mutation, protein C (PC), protein S (PS), antithrombin (AT) levels, and the presence of antiphospholipid antibodies (APLA, i.e., lupus anticoagulant, LAC, anti-cardiolipin and anti-b2-glycoprotein-1). Patients' hematological characteristics, additional thrombotic risk factors, history of venous/arterial thrombosis before and after AIHA diagnosis, and anticoagulant and/or antiplatelet therapies were retrospectively recorded. Results As shown in table 1, 59% of 92 enrolled patients were female with a median age at diagnosis of 70.5 years (range 24-89), and were classified as warm AIHA (50%), cold agglutinin disease (31.5%), mixed/atypical AIHA (9.8%), and Evans syndrome (association of AIHA and other immune cytopenia, 8.7%). Thrombophilia screening resulted positive in 19 patients (20.7%) including FVL (1.1%), F II (1.1%), APLA (10.8%), PC deficiency (1.1%), PS deficiency (2.2%), AT deficiency (2.2%), and more than one abnormality (2.2%). Additional risk factors considered were thrombosis prior to AIHA diagnosis, reported in 6 patients (7%, 3 venous and 3 arterial), and associated conditions (29%), including autoimmune disease (N=17), lymphoproliferative disease (N=7), myeloproliferative neoplasm (N=1), and paroxysmal nocturnal hemoglobinuria (N=1). Furthermore, 97% of subjects presented at least one risk factor (i.e., diabetes, obesity, bed rest, etc.) in addition to AIHA. Twenty-seven patients (28%) received anticoagulant prophylaxis after AIHA diagnosis, mainly short-term for hemolysis (42%) or surgery of lower limb fractures (37%), and long-term for atrial fibrillation in 24%; 22% of patients were on antiplatelet prophylaxis, and 4 patients had been splenectomized. Since AIHA diagnosis, 26 patients (28%) experienced thrombosis (77% venous, 23% arterial), with 33 total events (3 patients had &amp;gt; 1 event). Median hemoglobin and LDH at thrombosis were 8.6 g/dL (2-11.7), and 374 U/L (129-1873) respectively, indicating active hemolysis. No relationship was found with inherited thrombophilia abnormalities (3 patients, 8% experienced thrombosis vs 7, 10.5% who did not), whilst a significant association was noted with APLA positivity (p&amp;lt;0.05). Two patients with APLA experienced more than 1 event, one had 1 venous and 1 arterial event. Conclusions Along with disease activity and Evans syndrome, positivity for APLA appears the main predictor of thrombosis in AIHA and is therefore worth of testing, whilst extensive thrombophilia screening encompassing inherited abnormalities appears less useful.

Trombocitopenia Primária Imune com púrpura palpável: um relato de caso.

Immune thrombocytopenia is a relatively common bleeding disorder characterized by isolated destruction of platelets by autoantibodies, with a typically acute onset, benign course and self-limiting in most cases. The aim of this report is to present a rare case of Primary Immune Thrombocytopenia (ITP) with palpable purpura, an uncommon manifestation in this disease and little described in the literature. This is a 12-year-old female adolescent who presented with palpable purpura, ecchymosis and oral cavity bleeding associated with thrombocytopenia and anemia. Initial investigation excluded autoimmune diseases, vasculitis, lymphoproliferative diseases and coagulation disorders, in addition to the myelogram showing typical findings of ITP: hypercellular bone marrow with megakaryocytic hyperplasia and decreased thrombocytogenesis. Due to the diversity of clinical presentation and the possibility of atypical manifestations, the diagnosis is often challenging, as in the case of this patient in which the main finding on physical examination was the presence of palpable purpura.

A Stk4-Foxp3-NF-κB p65 transcriptional complex promotes Treg cell activation and homeostasis.

The molecular programs involved in regulatory T (Treg) cell activation and homeostasis remain incompletely understood. Here, we show that T cell receptor (TCR) signaling in Treg cells induces the nuclear translocation of serine/threonine kinase 4 (Stk4), leading to the formation of an Stk4-NF-κB p65-Foxp3 complex that regulates Foxp3- and p65-dependent transcriptional programs. This complex was stabilized by Stk4-dependent phosphorylation of Foxp3 on serine-418. Stk4 deficiency in Treg cells, either alone or in combination with its homolog Stk3, precipitated a fatal autoimmune lymphoproliferative disease in mice characterized by decreased Treg cell p65 expression and nuclear translocation, impaired NF-κB p65-Foxp3 complex formation, and defective Treg cell activation. In an adoptive immunotherapy model, overexpression of p65 or the phosphomimetic Foxp3S418E in Stk3/4-deficient Treg cells ameliorated their immune regulatory defects. Our studies identify Stk4 as an essential TCR-responsive regulator of p65-Foxp3-dependent transcription that promotes Treg cell-mediated immune tolerance.

Precision Medicine in the Treatment of Primary Immune Deficiency Patients With Disorders of Immune Dysregulation.

There are now more than 450 described monogenic germline mutations for inborn errors of immunity that result in the loss of expression, loss of function (LOF), or gain in function (GOF) of the encoded protein. Molecular characterization of these inborn errors of immunity has not only allowed us to characterize on a genetic basis these immune deficiency disorders but has provided a better understanding of the immunobiology of these inborn errors of immunity. More recently, these advances have allowed us to apply targeted therapy or precision medicine in their treatment. Of particular interest related to this review are those inborn errors of immunity that result in gain-of-function (GOF) genetic abnormalities. Many of these inborn errors of immunity fall into a new category referred to as diseases of immune dysregulation in which many of the patients not only exhibit an increased susceptibility to infection but also have a clinical phenotype associated with autoimmune processes and lymphoproliferative disease.

Adenosine Deaminase Type II Deficiency: Severe Chronic Neutropenia, Lymphoid Infiltration in Bone Marrow, and Inflammatory Features

ABSTRACT Deficiency of adenosine deaminase type 2 (DADA2) is an autoinflammatory disease characterized with immunologic, hematologic, and neurological features. Here, we presented two patients with severe persistent chronic neutropenia, which required differential diagnosis of congenital and autoimmune neutropenia, myelodysplastic syndrome (MDS), and primary immunodeficiency diseases, including autoimmune lymphoproliferative disease. The therapy of the disease except hematopoietic stem cell transplantation is a challenging experience.

Status of KRAS in iPSCs Impacts upon Self-Renewal and DifferentiationPropensity.

SummaryOncogenic KRAS mutations in hematopoietic stem cells cause RAS-associated autoimmune lymphoproliferative syndrome-like disease (RALD). KRAS plays essential roles in stemness maintenance in some types of stem cells. However, its roles in pluripotent stem cells (PSCs) are poorly understood. Here, we investigated the roles of KRAS on stemness in the context of induced PSCs (iPSCs). We used KRAS mutant (G13C/WT) and wild-type isogenic (WT/WT) iPSCs from the same RALD patients, as well as wild-type (WTed/WT) and heterozygous knockout (Δed/WT) iPSCs, both obtained by genome editing from the same G13C/WT clone. Compared with WT iPSCs, G13C/WT iPSCs displayed enforced retention of self-renewal and suppressed capacity for neuronal differentiation, while Δed/WT iPSCs showed normalized cellular characteristics similar to those of isogenic WTed/WT cells. The KRAS-ERK pathway, but not the KRAS-PI3K pathway, was shown to govern these G13C/WT-specific phenotypes, indicating the strong impact of the KRAS-ERK signaling upon self-renewal and differentiation propensity in human iPSCs.

Synergistic defects of novo FAS and homozygous UNC13D leading to autoimmune lymphoproliferative syndrome-like disease: A 10-year-old Chinese boy case report

Autoimmune lymphoproliferative syndrome (ALPS) usually presents in childhood with fever, nonmalignant splenomegaly and lymphadenopathy along with hemocytopenia. This case report describes a 10-year-old boy presenting with signs of autoimmune disease, splenomegaly, hepatomegaly and resistant hemocytopenia. Sirolimus controlled the relapsed thrombocytopenia after splenectomy. Sequencing of the FAS gene identified two spontaneous heterozygous mutations (c.234 T > G, p.D78E) (c.236dupA, p.P80Tfs*26). The boy's homozygous missense variation (c.2588G > A, p.G863D) (rs140184929) in UNC13D gene had been identified as being related to familial hemophagocytic lymphohistiocytosis (FHL). TCRαβ + CD4/CD8 double-negative T cells (markers of ALPS) were not significantly increased from the outset. Elevated cytokines, such as interferon (IFN)-γ, interleukin (IL)-6 and tumor necrosis factor α decreased to normal levels after splenectomy whereas IL-10 remained high. Immunological analysis of the patient revealed a marked depletion of forkhead-box P3+ expressing regulatory T cells (Treg) and Th17 cells. The obtained data demonstrate that mutations to FAS and UNC13D which result in overwhelming T-cell and macrophage activation, one associated with inhibited Treg cell development and a severe ALPS-like symptom. Therefore, we propose that variations of UND13D may be a risk factor of ALPS development.

Delayed Diagnosis and Complications of Predominantly Antibody Deficiencies in a Cohort of Australian Adults.

Predominantly antibody deficiencies (PADs) are the most common type of primary immunodeficiency in adults. PADs frequently pass undetected leading to delayed diagnosis, delayed treatment, and the potential for end-organ damage including bronchiectasis. In addition, PADs are frequently accompanied by comorbid autoimmune disease, and an increased risk of malignancy. To characterize the diagnostic and clinical features of adult PAD patients in Victoria, Australia. We identified adult patients receiving, or having previously received immunoglobulin replacement therapy for a PAD at four hospitals in metropolitan Melbourne, and retrospectively characterized their clinical and diagnostic features. 179 patients from The Royal Melbourne, Alfred and Austin Hospitals, and Monash Medical Centre were included in the study with a median age of 49.7 years (range: 16-87 years), of whom 98 (54.7%) were female. The majority of patients (116; 64.8%) met diagnostic criteria for common variable immunodeficiency (CVID), and 21 (11.7%) were diagnosed with X-linked agammaglobulinemia (XLA). Unclassified hypogammaglobulinemia (HGG) was described in 22 patients (12.3%), IgG subclass deficiency (IGSCD) in 12 (6.7%), and specific antibody deficiency (SpAD) in 4 individuals (2.2%). The remaining four patients had a diagnosis of Good syndrome (thymoma with immunodeficiency). There was no significant difference between the age at diagnosis of the disorders, with the exception of XLA, with a median age at diagnosis of less than 1 year. The median age of reported symptom onset was 20 years for those with a diagnosis of CVID, with a median age at diagnosis of 35 years. CVID patients experienced significantly more non-infectious complications, such as autoimmune cytopenias and lymphoproliferative disease, than the other antibody deficiency disorders. The presence of non-infectious complications was associated with significantly reduced survival in the cohort. Our data are largely consistent with the experience of other centers internationally, with clear areas for improvement, including reducing diagnostic delay for patients with PADs. It is likely that these challenges will be in part overcome by continued advances in implementation of genomic sequencing for diagnosis of PADs, and with that opportunities for targeted treatment of non-infectious complications.

RASGRP1 mutation in autoimmune lymphoproliferative syndrome-like disease

Autoimmune lymphoproliferative syndrome (ALPS) is a genetic disorder of lymphocyte homeostasis due to impaired apoptosis. It was initially regarded as a very rare disease, but recent studies show that it may be more common than previously thought. Defects in a couple of genes have been identified in a proportion of patients with ALPS, but around one-third of such patients remain undefined genetically. We describe 2 siblings presenting with ALPS-like disease. This study aimed to identify the genetic cause responsible for this phenotype. Whole-exome sequencing and molecular and functional analyses were used to identify and characterize the genetic defect. Clinical and immunological analysis was also performed and reported. The 2 patients presented with chronic lymphadenopathy, hepatosplenomegaly, autoimmune hemolytic anemia, immune thrombocytopenia, and the presence of antinuclear autoantibody and other autoantibodies, but normal double-negative T cells. They also suffered from recurrent infections. Novel compound heterozygous mutations of RASGRP1 encoding Ras guanyl nucleotide releasing protein 1 were identified in the 2 siblings. The mutations impaired T-cell receptor signaling, leading to defective T-cell activation and proliferation, as well as impaired activation-induced cell death of T cells. This study shows for the first time that RASGRP1 mutation should be considered in patients with ALPS-like disease. We also propose to investigate the intracellular proteins involved in the T-cell receptor signaling pathway in similar patients but with unknown genetic cause.

Autoimmune lymphoproliferative syndrome-like disease in patients with LRBA mutation

Mutations in LPS-responsive and beige-like anchor (LRBA) gene were recently described in patients with combined immunodeficiency, enteropathy and autoimmune cytopenia. Here, we extend the clinical and immunological phenotypic spectrum of LRBA associated disorders by reporting on three patients from two unrelated families who presented with splenomegaly and lymphadenopathy, cytopenia, elevated double negative T cells and raised serum Fas ligand levels resembling autoimmune lymphoproliferative syndrome (ALPS) and one asymptomatic patient. Homozygous loss of function mutations in LRBA were identified by whole exome analysis. Similar to ALPS patients, Fas mediated apoptosis was impaired in LRBA deficient patients, while apoptosis in response to stimuli of the intrinsic mitochondria mediated apoptotic pathway was even enhanced. This manuscript illustrates the phenotypic overlap of other primary immunodeficiencies with ALPS-like disorders and strongly underlines the necessity of genetic diagnosis in order to provide early correct diagnosis and subsequent care.

Déficit immunitaire commun variable (DICV) : caractéristiques cliniques et immunologiques de 29 patients algériens

PurposeCommon variable immunodeficiency (CVID) is the commonest symptomatic primary immunodeficiency. It is characterized by a defect of antibody production, recurrent respiratory tract infections and increased occurrence of auto-immune discords and lymphoproliferative disease. MethodsThis retrospective study was conducted on 29 patients fulfilling the classical CVID definition. Blood tests included immunoglobulin measurement and lymphocyte subpopulations phenotyping. ResultsThis study includes 29 patients. The mean age at diagnosis was 23years. Recurrent upper and lower bacterial respiratory tract infections were common in almost all patients. Five patients developed auto-immune conditions and six had lymphoproliferative disease. Decreased IgG was found in almost all patients. Low IgA and IgM levels were found in 89.6 % and 65.5 % of cases respectively. Abnormal T and/or B phenotype was found in 75 % of cases; the most common abnormalities were decreased circulating B (54.2 %) and T CD4+ (41.7 %) cells and inversion of the CD4/CD8 ratio (70.8 %). Patients with decreased circulating B and T CD4+ cells were significantly more likely to have auto-immune cytopenias and lymphoproliferative disease. ConclusionsOur study confirms the heterogeneity of CVID. A patient's classification is necessary to define homogeneous groups of patients and to characterize specific molecular abnormalities in each group.

Multiple CD11c+ Cells Collaboratively Express IL-1β To Modulate Stromal Vascular Endothelial Growth Factor and Lymph Node Vascular–Stromal Growth

Lymphadenopathy in autoimmune and other lymphoproliferative diseases is in part characterized by immunoblasts and vascular proliferation. The lymph node vasculature, along with the nonvascular stromal compartment, supports lymphocyte function, and targeting vascular-stromal expansion in inflamed nodes may modulate lymphocyte function in disease. CD11c(+) cells are essential for vascular-stromal proliferation and the upregulation of vascular endothelial growth factor (VEGF) needed for vascular proliferation. However, targetable CD11c(+) cell-derived molecular mediators, the identity of relevant CD11c(+) cells, and whether CD11c(+) cells directly stimulate VEGF-expressing stromal cells are poorly understood. In this study we show that CD11c(+) CD11b(+) CCR2-dependent monocytes and CCR7-dependent dendritic cells express IL-1β. IL-1β blockade, IL-1β deficiency in radiosensitive cells, and CCR2/CCR7 double deficiency but not single deficiency all attenuate immunization-induced vascular-stromal proliferation. gp38(+) stromal fibroblastic reticular cells (FRCs) that express VEGF are enriched for Thy1(+) cells and partially overlap with CCL21-expressing FRCs, and FRC VEGF is attenuated with IL-1β deficiency or blockade. IL-1β localizes to the outer borders of the T zone, where VEGF-expressing cells are also enriched. Ex vivo, CD11b(+) cells enriched for IL-1β(+) cells can directly induce cultured gp38(+)Thy1(+) FRCs to upregulate VEGF. Taken together, these results suggest a mechanism whereby multiple recruited CD11c(+) populations express IL-1β and directly modulate FRC function to help promote the initiation of vascular-stromal growth in stimulated lymph nodes. These data provide new insight into how CD11c(+) cells regulate the lymph node vascular-stromal compartment, add to the evolving understanding of functional stromal subsets, and suggest a possible utility for IL-1β blockade in preventing inflammatory lymph node growth.

IL-17 protects T cells from apoptosis and contributes to development of ALPS-like phenotypes

AbstractIn autoimmune/lymphoproliferative syndrome (ALPS), defective Fas death receptor function causes lymphadenomegaly/splenomegaly, the expansion of T-cell receptor αβ+ CD4/CD8 double-negative T cells, and frequent development of hematologic autoimmunity. Dianzani autoimmune lymphoproliferative disease (DALD) has a similar phenotype but lacks the expansion of double-negative T cells. This work shows that patients with ALPS and DALD have high serum levels of interleukin 17A (IL-17A), IL-17F, and IL-17AF, which are involved in several autoimmune diseases, and that their T cells show increased secretion of these cytokines upon activation in vitro. The following data indicate that these cytokines may contribute to ALPS and DALD: (1) recombinant IL-17A and IL-17F significantly inhibit Fas-induced cell death in Fas-sensitive T cells from healthy donors; (2) this inhibitory effect is also induced by the patients' serum and is reversed by anti–IL-17A antibodies; (3) IL-17A neutralization substantially increases Fas-induced cell death in T cells from ALPS and DALD patients in vitro; and (4) treatment with anti–IL-17A antibodies ameliorates the autoimmune manifestations and, at a lesser extent, the lymphoproliferative phenotype and prolongs survival in MRLlpr/lpr mice, which are an animal model of ALPS. These data suggest that IL-17A and IL-17F could be targeted therapeutically to improve Fas function in ALPS and DALD.

Successful treatment of enteropathy associated with common variable immunodeficiency

Successful treatment of enteropathy associated with common variable immunodeficiency

AB0472 Primary and secondary central nervous system vasculitis: clinical manifestations, laboratory findings, neuroimaging, and treatment analysis

BackgroundPrimary central nervous system vasculitis (PCNSV) is a challenging clinical problem due to itsnon- specific signs and symptoms, inaccessibility of the central nervous system (CNS) tissue for pathologic examination, lack...

Critical role of Th17 cells in development of autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) is defined as the increased destruction of red blood cells (RBCs) in the presence of anti-RBC autoantibodies with or without complement activation. However, the underlying mechanism for the development of AIHA remains largely unclear. In this study, we carefully evaluated the potential role of Th17 cells in the development of AIHA. We found an elevated frequency of Th17 cells in patients with AIHA, which were closely correlated with their disease activity, including the level of anti-RBC IgG antibodies, hemoglobin, serum C3, and lactate dehydrogenase activity. Furthermore, we observed that interleukin (IL)-17 was also closely correlated with the disease activity in AIHA patients. To further elucidate the potential role of Th17 cells in induction of AIHA, we used the Marshall-Clarke and Playfair model of murine AIHA. Notably, we found that Th17 cells affected development of AIHA by enhancing the adaptive humoral responses. Specifically, we found that adoptive transfer of Th17 cells heightened the initial anti-rat RBC antibody responses and concomitantly increased the onset of AIHA. In addition, invivo neutralization of IL-17 abrogated the development of AIHA, while initiation of anti-rat RBC IgG responses and induction of AIHA in IL-17(-/-) mice were impaired. Our findings suggest that Th17 cells contribute to the development of AIHA, which could facilitate our better understanding of AIHA pathogenesis and provide clues to developing novel forms of immunotherapy against AIHA.

The -346T polymorphism of the SH2D1A gene is a risk factor for development of autoimmunity/lymphoproliferation in males with defective Fas function

Inherited defects decreasing function of the Fas death receptor cause autoimmune lymphoproliferative syndrome (ALPS) and its variant Dianzani autoimmune lymphoproliferative disease (DALD). Since a deleterious mutation of the SH2D1A gene protects MRLlpr/lpr mice from ALPS development, we investigated the role of SH2D1A, located in the X chromosome, in 51 patients with ALPS or DALD by mutational screening of coding and regulative sequences. Allelic frequency of the -346C>T polymorphism was different in male patients and controls (-346T: 61% vs 36%, p = 0.01), with similar frequencies in ALPS and DALD. By contrast, no differences were found among females or between the controls and patients with multiple sclerosis (229 males, 157 females). Further analyses showed that -346C was a methylation site in CD8(+) T and natural killer cells, and SH2D1A expression was higher in -346T than in -346C males. Finally, in vitro-activated T cells from -346T males produced lower amounts of interferon-γ than those from -346C males. These data suggest that -346T is a predisposing factor for ALPS and DALD in males possibly because of its effect on SAP expression influencing the T-cell response.