Kaposi sarcoma–associated herpesvirus/human herpesvirus 8 is associated with multicentric Castleman disease (MCD) and primary effusion lymphoma (PEL). In MCD, infected B cells, although polyclonal, ...express a monotypic immunoglobulin Mλ phenotype, probably through editing toward λ light chain in mature B cells. They are considered to originate from pre–germinal center (GC) naive B cells. Both viral and human interleukin-6 contribute to the plasmacytic differentiation of these cells, and viral replication can be observed in some infected cells. PEL cells are clonal B cells considered as GC/post-GC B cells. One can also hypothesize that they originate from the same infected naive B cells and that additional factors could be responsible for their peculiar phenotype.
Summary
The spectrum of Castleman disease (CD) has considerably extended since its first description in 1956. Recently, an international collaborative working group has reached consensus on the ...diagnostic criteria and classification of CD. We herein report 273 patients with lymph node histopathology consistent with CD and investigate the newly established diagnostic criteria. Twenty of these patients with Castleman‐like histopathology were removed from analyses, because they were diagnosed with an exclusionary disorder (18 with haematological malignancy). Among the 253 remaining patients, 57 were considered unicentric CD (UCD), 169 were multicentric CD associated with Human Herpesvirus 8 (HHV‐8+MCD), including 140 patients with human immunodeficiency virus (HIV) infection and 29 patients without HIV infection, and 27 were HHV‐8 negative/idiopathic multicentric CD (iMCD). 2‐(18F)fluoro‐2‐deoxy‐D‐glucose positron emission tomography/computed tomography was useful in 62 patients for staging/classification of the disease and for excluding associated lymphoma. UCD was mainly associated with hyaline‐vascular histopathological features, and most patients were asymptomatic. Of the 27 patients that we had originally diagnosed with iMCD, 26 met the newly established diagnostic criteria. Patients with iMCD and HHV‐8+ MCD demonstrated similar characteristics, including fever, splenomegaly, cytopenia and inflammatory symptoms. However, the disease was more aggressive in HHV‐8+ MCD, particularly in HIV‐infected patients.
Background Acquired hemophagocytic lymphohistiocytosis (HLH) is a life-threatening event that usually occurs as a complication of immunodeficiency. Lung involvement in HLH has received little ...attention. This article describes lung involvement in HLH and assesses whether it affects the prognosis. Methods We retrospectively studied 219 patients with HLH admitted to a national reference center over a 14-year period, including 118 (54%) with lung involvement. Results Dyspnea and cough were the most common onset symptoms. Radiographs revealed interstitial infiltrates with centrilobular nodules, ill-defined consolidation, or localized ground-glass opacities. Pleural effusions and mediastinal lymphadenopathies were found in approximately one-half of the patients. One or more causes of lung involvement were documented in 91 of 118 patients (77.1%) and included infection (n = 52), pulmonary edema (n = 34), and malignancies (n = 22 mostly lymphoma). HLH-specific treatment combined with treatment of the cause of lung involvement improved respiratory function in only 67 of the 188 patients (56.7%). Hospital mortality was higher in patients with lung involvement (52.5% vs 20%). Infection as the cause of lung involvement was the only determinant of death (56% vs 30%; P = .004). Conclusions Lung involvement is common and of poor prognosis in patients with HLH. Studies should assess whether specific diagnostic and therapeutic strategies are warranted in patients with HLH and lung involvement.
Autosomal dominant hyper-IgE syndrome (AD-HIES) is typically caused by dominant-negative (DN) STAT3 mutations. Patients suffer from cold staphylococcal lesions and mucocutaneous candidiasis, severe ...allergy, and skeletal abnormalities. We report 12 patients from 8 unrelated kindreds with AD-HIES due to DN IL6ST mutations. We identified seven different truncating mutations, one of which was recurrent. The mutant alleles encode GP130 receptors bearing the transmembrane domain but lacking both the recycling motif and all four STAT3-recruiting tyrosine residues. Upon overexpression, the mutant proteins accumulate at the cell surface and are loss of function and DN for cellular responses to IL-6, IL-11, LIF, and OSM. Moreover, the patients' heterozygous leukocytes and fibroblasts respond poorly to IL-6 and IL-11. Consistently, patients with STAT3 and IL6ST mutations display infectious and allergic manifestations of IL-6R deficiency, and some of the skeletal abnormalities of IL-11R deficiency. DN STAT3 and IL6ST mutations thus appear to underlie clinical phenocopies through impairment of the IL-6 and IL-11 response pathways.
Background Activated phosphoinositide 3-kinase δ syndrome (APDS) 2 (p110δ-activating mutations causing senescent T cells, lymphadenopathy, and immunodeficiency PASLI–R1), a recently described primary ...immunodeficiency, results from autosomal dominant mutations in PIK3R1 , the gene encoding the regulatory subunit (p85α, p55α, and p50α) of class IA phosphoinositide 3-kinases. Objectives We sought to review the clinical, immunologic, and histopathologic phenotypes of APDS2 in a genetically defined international patient cohort. Methods The medical and biological records of 36 patients with genetically diagnosed APDS2 were collected and reviewed. Results Mutations within splice acceptor and donor sites of exon 11 of the PIK3R1 gene lead to APDS2. Recurrent upper respiratory tract infections (100%), pneumonitis (71%), and chronic lymphoproliferation (89%, including adenopathy 75%, splenomegaly 43%, and upper respiratory tract lymphoid hyperplasia 48%) were the most common features. Growth retardation was frequently noticed (45%). Other complications were mild neurodevelopmental delay (31%); malignant diseases (28%), most of them being B-cell lymphomas; autoimmunity (17%); bronchiectasis (18%); and chronic diarrhea (24%). Decreased serum IgA and IgG levels (87%), increased IgM levels (58%), B-cell lymphopenia (88%) associated with an increased frequency of transitional B cells (93%), and decreased numbers of naive CD4 and naive CD8 cells but increased numbers of CD8 effector/memory T cells were predominant immunologic features. The majority of patients (89%) received immunoglobulin replacement; 3 patients were treated with rituximab, and 6 were treated with rapamycin initiated after diagnosis of APDS2. Five patients died from APDS2-related complications. Conclusion APDS2 is a combined immunodeficiency with a variable clinical phenotype. Complications are frequent, such as severe bacterial and viral infections, lymphoproliferation, and lymphoma similar to APDS1/PASLI-CD. Immunoglobulin replacement therapy, rapamycin, and, likely in the near future, selective phosphoinositide 3-kinase δ inhibitors are possible treatment options.
Epstein-Barr virus (EBV) infection in humans is a major trigger of malignant and nonmalignant B cell proliferations. CD27 is a co-stimulatory molecule of T cells, and inherited CD27 deficiency is ...characterized by high susceptibility to EBV infection, though the underlying pathological mechanisms have not yet been identified. In this study, we report a patient suffering from recurrent EBV-induced B cell proliferations including Hodgkin's lymphoma because of a deficiency in CD70, the ligand of CD27. We show that EBV-specific T lymphocytes did not expand properly when stimulated with CD70-deficient EBV-infected B cells, whereas expression of CD70 in B cells restored expansion, indicating that CD70 on B cells but not on T cells is required for efficient proliferation of T cells. CD70 was found to be up-regulated on B cells when activated and during EBV infection. The proliferation of T cells triggered by CD70-expressing B cells was dependent on CD27 and CD3 on T cells. Importantly, CD27-deficient T cells failed to proliferate when stimulated with CD70-expressing B cells. Thus, the CD70-CD27 pathway appears to be a crucial component of EBV-specific T cell immunity and more generally for the immune surveillance of B cells and may be a target for immunotherapy of B cell malignancies.
Inherited CTPS1, CD27, and CD70 deficiencies in humans have revealed key factors of T‐lymphocyte expansion, a critical prerequisite for an efficient immunity to Epstein–Barr virus (EBV) infection. ...RASGRP1 is a T‐lymphocyte‐specific nucleotide exchange factor known to activate the pathway of MAP kinases (MAPK). A deleterious homozygous mutation in RASGRP1 leading to the loss RASGRP1 expression was identified in two siblings who both developed a persistent EBV infection leading to Hodgkin lymphoma. RASGRP1‐deficient T cells exhibited defective MAPK activation and impaired proliferation that was restored by expression of wild‐type RASGRP1. Similar defects were observed in T cells from healthy individuals when RASGRP1 was downregulated. RASGRP1‐deficient T cells also exhibited decreased CD27‐dependent proliferation toward CD70‐expressing EBV‐transformed B cells, a crucial pathway required for expansion of antigen‐specific T cells during anti‐EBV immunity. Furthermore, RASGRP1‐deficient T cells failed to upregulate CTPS1, an important enzyme involved in DNA synthesis. These results show that RASGRP1 deficiency leads to susceptibility to EBV infection and demonstrate the key role of RASGRP1 at the crossroad of pathways required for the expansion of activated T lymphocytes.
Synopsis
RASGRP1 deficiency is characterized by a high susceptibility to develop Epstein‐Barr virus (EBV)‐driven B‐cell lymphoproliferative disorders such as B‐cell lymphoma like Hodgkin lymphoma. This is caused by defective expansion of activated T cells required for an efficient immune response to EBV.
RASGRP1 is a critical factor of T‐cell proliferation including CD27‐, CD70‐ and CTPS1‐dependent pathways.
RASGRP1 is required for expression of genes involved cell proliferation.
This study emphasizes that T‐cell expansion is a critical step in immunity to EBV.
RASGRP1 deficiency is characterized by a high susceptibility to develop Epstein‐Barr virus (EBV)‐driven B‐cell lymphoproliferative disorders such as B‐cell lymphoma like Hodgkin lymphoma. This is caused by defective expansion of activated T cells required for an efficient immune response to EBV.
Epstein-Barr virus (EBV) preferentially infects epithelial cells and B lymphocytes and sometimes T and NK lymphocytes. Persistence of EBV-infected cells results in severe lymphoproliferative ...disorders (LPDs). Diagnosis of EBV-driven T or NK cell LPD and chronic active EBV diseases (CAEBV) is difficult, often requiring biopsies. Herein, we report a flow-FISH cytometry assay that detects cells expressing EBV-encoded small RNAs (EBERs), allowing rapid identification of EBV-infected cells among PBMCs. EBV-infected B, T, and/or NK cells were detectable in various LPD conditions. Diagnosis of CAEBV in 22 patients of Caucasian and African origins was established. All exhibited circulating EBV-infected T and/or NK cells, highlighting that CAEBV is not restricted to native American and Asian populations. Proportions of EBV-infected cells correlated with blood EBV loads. We showed that EBV-infected T cells had an effector memory activated phenotype, whereas EBV-infected B cells expressed plasma cell differentiation markers. Thus, this method achieves accurate and unambiguous diagnoses of different forms of EBV-driven LPD and represents a powerful tool to study their pathophysiological mechanisms.
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