Significance of hypergammaglobulinemia in patients with chronic myelomonocytic leukemia.

Chronic inflammation is often indicated by a relative increase in the gamma globulin fraction in the serum electrophoresis. In a retrospective study, we analyzed the prevalence of relative hypergammaglobulinemia in 60 patients with chronic myelomonocytic leukemia (CMML), its potential prognostic impact, and potential correlations with laboratory and molecular features. Relative hypergammaglobulinemia (> 20%) was found in 25/60 (42%) patients. The median survival of patients with relative hypergammaglobulinemia was significantly shorter than in patients without hypergammaglobulinemia (10 vs. 24 months, p = 0.018). There was no difference between the groups regarding leukocyte count, hemoglobin value, and platelet count, but a higher prevalence of NRAS mutations and a lower prevalence of ZRSR2 mutations in patients with hypergammaglobulinemia. Our results show that hypergammaglobulinemia is present in a proportion of CMML patients and that this abnormality is associated with poor overall survival. The role of chronic inflammation in the pathophysiology of CMML needs to be further investigated.

Unusual phenotype in patients with a hypomorphic mutation in the DCLRE1C gene: IgG hypergammaglobulinemia with IgA and IgE deficiency.

The nuclease Artemis is a enzyme for V(D)J recombination allowing for the creation of T and B lymphocytes as well as for the repair of radiation-induced DNA double strand breaks encoded by the DCLRE1C gene. Artemis-null mutations are a known cause of severe combined immunodeficiencies (SCIDs) with radiosensitivity. Hypomorphic mutations in Artemis have been reported to cause a "leaky SCID"" phenotype, typically with hypogammaglobulinemia. We present four patients, all harboring the same unique hypomorphic mutation in the DCLRE1C gene, an 8-base pair insertion (c.1299_1306dup, p.Cys436*) presenting with a relatively mild phenotype including pulmonary infectious EBV-related lymphoproliferative diseases, an autoimmune phenomenon. Non-typical findings of IgG hypergammaglobulinemia accompanied by IgA and IgE deficiency were recorded in all patients. The typical viral, fungal, and opportunistic infections were absent, and patients reached a relatively old age.

Kaposi's Sarcoma-Associated Herpesvirus Latency Locus Renders B Cells Hyperresponsive to Secondary Infections.

Kaposi's sarcoma-associated herpesvirus (KSHV) induces B cell hyperplasia and neoplasia, such as multicentric Castleman's disease (MCD) and primary effusion lymphoma (PEL). To explore KSHV-induced B cell reprogramming in vivo, we expressed the KSHV latency locus, inclusive of all viral microRNAs (miRNAs), in B cells of transgenic mice in the absence of the inhibitory FcγRIIB receptor. The BALB/c strain was chosen as this is the preferred model to study B cell differentiation. The mice developed hyperglobulinemia, plasmacytosis, and B lymphoid hyperplasia. This phenotype was ameliorated by everolimus, which is a rapamycin derivative used for the treatment of mantle cell lymphoma. KSHV latency mice exhibited hyperresponsiveness to the T-dependent (TD) antigen mimic anti-CD40 and increased incidence of pristane-induced inflammation. Lastly, the adaptive immunity against a secondary infection with Zika virus (ZIKV) was markedly enhanced. These phenotypes are consistent with KSHV lowering the activation threshold of latently infected B cells, which may be beneficial in areas of endemicity, where KSHV is acquired in childhood and infections are common.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) establishes latency in B cells and is stringently linked to primary effusion lymphoma (PEL) and the premalignant B cell hyperplasia multicentric Castleman's disease (MCD). To investigate potential genetic background effects, we expressed the KSHV miRNAs in BALB/c transgenic mice. BALB/c mice are the preferred strain for B cell hybridoma development because of their propensity to develop predictable B cell responses to antigen. The BALB/c latency mice exhibited a higher incidence of B cell hyperplasia as well as sustained hyperglobulinemia. The development of neutralizing antibodies against ZIKV was augmented in BALB/c latency mice. Hyperglobulinemia was dampened by everolimus, a derivative of rapamycin, suggesting a role for mTOR inhibitors in managing immune activation, which is hallmark of KSHV infection as well as HIV infection.

TACI deletion protects against progressive murine lupus nephritis induced by BAFF overexpression.

B cells are known to promote the pathogenesis of systemic lupus erythematosus (SLE) via the production of pathogenic anti-nuclear antibodies. However, the signals required for autoreactive B cell activation and the immune mechanisms whereby B cells impact lupus nephritis pathology remain poorly understood. The B cell survival cytokine B cell activating factor of the TNF Family (BAFF) has been implicated in the pathogenesis of SLE and lupus nephritis in both animal models and human clinical studies. Although the BAFF receptor has been predicted to be the primary BAFF family receptor responsible for BAFF-driven humoral autoimmunity, in the current study we identify a critical role for signals downstream of Transmembrane Activator and CAML Interactor (TACI) in BAFF-dependent lupus nephritis. Whereas transgenic mice overexpressing BAFF develop progressive membranoproliferative glomerulonephritis, albuminuria and renal dysfunction, TACI deletion in BAFF-transgenic mice provided long-term (about 1 year) protection from renal disease. Surprisingly, disease protection in this context was not explained by complete loss of glomerular immune complex deposits. Rather, TACI deletion specifically reduced endocapillary, but not mesangial, immune deposits. Notably, although excess BAFF promoted widespread breaks in B cell tolerance, BAFF-transgenic antibodies were enriched for RNA- relative to DNA-associated autoantigen reactivity. These RNA-associated autoantibody specificities were specifically reduced by TACI or Toll-like receptor 7 deletion. Thus, our study provides important insights into the autoantibody specificities driving proliferative lupus nephritis, and suggests that TACI inhibition may be novel and effective treatment strategy in lupus nephritis.

Hyperimmunoglobulin syndrome due to CD40 deficiency: possibly the first case from India.

Hyperimmunoglobulin M (HIGM) type 3 due to CD40 deficiency is a very rare syndrome. Only 16 cases have been reported thus far. The clinical presentation is very variable. We present the first case of this rare disorder from India. The case is of a two-and-a-half-year-old female, with a history of repeated episodes of skin infections and diarrhea since birth. Laboratory evaluation revealed elevated absolute lymphocyte count and an absolute neutrophil count (ANC) of 1026/mm3. The lymphocyte subset analysis showed normal absolute counts of Natural Killer (NK) cells and elevated absolute counts of T-cells (CD4 and CD8) and B-cells. The serum immunoglobulin estimation showed low levels of IgG, IgA, IgE and an elevated level of IgM. The CD154 analysis was normal and expression of CD40 was absent on the B-cells. Molecular analysis showed a novel mutation, with deletion of 3bp (AAG) [p.Glu107GlyfsX84] in the homozygous state, in the CD40 gene. Thus the patient was diagnosed as HIGM type 3. The parents were screened and counseled regarding prenatal diagnosis at the time of next pregnancy.

Cryptococcal meningoencephalitis in a patient with hyper immunoglobulin M (IgM) syndrome: a case report.

BACKGROUND: Cryptococcal meningoencephalitis is an opportunistic infection that predominantly affects immunocompromised patients. Hyper immunoglobulin M syndrome is a primary immunodeficiency syndrome that increases susceptibility to several opportunistic infections. Here, we report a case of cryptococcal meningoencephalitis in the context of hyper immunoglobulin M syndrome, a situation that has been reported very few times and whose management is not clearly defined. We describe our management of this case and the outcome of the patient to help in future similar situations. CASE PRESENTATION: The patient is a 19-year-old Caucasian male student diagnosed with X-linked hyper immunoglobulin M syndrome and treated chronically with weekly intravenous immunoglobulin and daily sulfamethoxazole-trimethoprim. He was admitted to the infectious diseases ward because of headache, diplopia and a cerebral-spinal fluid analysis revealing cryptococcal meningoencephalitis. The patient was treated with liposomal amphotericin and flucytosine with a favorable outcome. Maintenance therapy with fluconazole has continued and will be sustained for 6 months following his upcoming bone marrow transplantation. CONCLUSION: Monitoring for cryptococcal meningoencephalitis should be considered in patients with primary immunodeficiencies, as clinical manifestations may go unnoticed. In these patients, it is expected that chronic treatment with fluconazole will be the only treatment that will prevent reinfection or reactivation, and therefore should be kept at least until bone marrow transplant, the only curative treatment, is performed. It may, however, lead to intolerable side effects and hepatic toxicity.

Cooperative immunoregulatory function of the transmembrane adaptor proteins SIT and LAX.

Lymphocyte activation is crucial for the generation of immune responses. In vitro studies have demonstrated that TRAPs are critical regulators of lymphocyte activation. However, more recent in vivo studies have demonstrated that with the exception of LAT, TRAPs, such as SIT, NTAL, and LAX, only minimally affect immune cell functions. Additional studies have suggested that the mild or the apparent lack of a phenotype displayed by most TRAP KO mice may be explained by functional redundancy among this family of adaptors. In fact, it has been shown that the phenotype of NTAL/LAT or SIT/TRIM double-deficient mice is more severe than that of the single KOs. Here, we have evaluated whether SIT and the related transmembrane adaptor LAX have overlapping functions by generating SIT/LAX DKO mice. We show that DKO, in contrast to single KO mice, accumulate large numbers of activated CD4(+) T cells in the spleen. Moreover, conventional B cells from DKO mice are hyperproliferative upon CD40 stimulation. Additionally, we found that DKO mice displayed an expansion of the B1 cell pool in the peritoneal cavity, hypergammaglobulinaemia, and an enhanced immune response to the T1-independent antigen, TNP-LPS. Finally, we demonstrate that SIT/LAX double deficiency resulted in a more pronounced breakdown of peripheral tolerance and the development of autoimmunity characterized by ANAs and renal disease (glomerulonephritis and proteinuria). Collectively, our data indicate that SIT and LAX are important negative regulators of immune responses that functionally cooperate.

Granulomatous skin lesions, severe scrotal and lower limb edema due to mycobacterial infections in a child with complete IFN-γ receptor-1 deficiency.

Interferon-γ receptor-1 (IFNγR1) deficiency is caused by mutations in the IFNγR1 gene and is characterized mainly by susceptibility to mycobacterial disease. Herein, we report an 8-month-old boy with complete recessive IFNγR1 deficiency, afflicted by recurrent mycobacterial diseases with Mycobacterium bovis, Mycobacterium tuberculosis, Mycobacterium avium intracellulare and Mycobacterium fortuitum. Genetic analysis showed a homozygous mutation (106insT) in the IFNγR1 gene leading to complete IFNγR1 deficiency. In addition, he had atypical mycobacterial skin lesions caused by M. avium intracellulare and developed scrotal and lower limb lymphedema secondary to compression of large and fixed inguinal lymphadenopathies. Hematopoietic stem cell transplantation was performed from a matched unrelated donor at 5 years of age; however, he died at 9 months post-transplant. To our knowledge, the patient is the first case with IL-12/IFN-γ pathway defect and severe lymphedema. We have also reviewed and summarized the literature related with IFNγR1 deficiency.

Phenotypic heterogeneity in a family with a CD40 ligand intracellular domain mutation.

We describe a family with the rare mutation R11X that leads to a truncated CD40 ligand (CD40L) missing the intracellular domain. The index case had detectable CD40L expression and presented at the age of 41 years with cerebral toxoplasmosis. A brother and two nephews were also identified as having the same mutation but exhibited milder and variable phenotypes. The older affected nephew had a moderately depressed immunoglobulin G level and a history of pneumonia at 4 months of age. The younger nephew suffered from sinusitis with normal immunoglobulin levels. Both nephews had absent antibody responses to a protein antigen with conserved responses to polysaccharide antigens. The two sisters of the index case are carriers who had elevated levels of IgM but remain well. This mutation may affect CD40 ligand function by reducing cell surface levels, diminishing CD40 interaction or disrupting CD40L intracellular signalling in T cells. The variable phenotype in members of this family offers an opportunity to further understand the CD40-CD40L signalling pathway in human immune responses.

Targeted overexpression of an activated N-ras gene results in B-cell and plasma cell lymphoproliferation and cooperates with c-myc to induce fatal B-cell neoplasia.

Multiple myeloma is an incurable malignant expansion of plasma cells in the bone marrow. Although there is no pathognomonic genetic lesion among multiple myeloma patients, activation of the ras gene has been identified as a common mutation. We have previously described the use of the 3' κ immunoglobulin light chain enhancer (3'KE) to target transgenic expression in murine B and plasma cells, resulting in bcl-X(L) and c-myc-driven murine models of multiple myeloma. In this report, we characterize the role of activated mutant N-ras in B and plasma cells in transgenic mice. We constructed transgenic mice that use 3'KE to direct expression of a mutant activated N-ras. We also crossed the N-ras mice with mice bearing a c-myc transgene to study the cooperative effects of the transgenic constructs. Mice were sacrificed when moribund or at specific time intervals and characterized by serology, light microscopy, and flow cytometry. The transgenic N-ras animals develop B- and plasma cell lymphoproliferation, and aged mice develop immunoglobulinemia, renal hyaline tubular casts, and microscopic foci of abnormal plasma cells in extramedullary sites, including the liver and kidney. Bitransgenic 3'KE/N-Ras V12 × Eµ-c-Myc mice develop fatal B-cell neoplasia, with a median survival of 10 weeks. These data indicate that activated N-ras can play a role in B- and plasma cell homeostasis and that activated N-Ras and c-Myc can cooperate to induce B-cell neoplasia.

[Autoinflammatory syndromes]. / Síndromes autoinflamatorios.

Autoinflammatory syndromes are characterised by recurrent or persistent inflammation with no increase in the antibody titers or antigen-specific T lymphocytes, and absence of infection. Initially, they included the hereditary periodic fever syndromes, a group of innate immune system monogenic diseases characterised by recurrent febrile episodes, with different characteristics, duration and interval, accompanied by other symptoms. Secondary amyloidosis is a complication in this group. The advances in the last few years has led to the identification of susceptible genes, new proteins, and characterising mechanisms and pathogenic routes that have led to an improvement in the diagnosis and establishing more effective treatments. Among these routes, are the changes in the inflammasome components, a group of cytoplasmic proteins that regulate the production of several inflammatory response mediators. The initial group of monogenic autoinflammatory diseases have increased in the last few years, due to including several polygenic hereditary diseases.

A novel transgenic mouse model of the human multiple myeloma chromosomal translocation t(14;16)(q32;q23).

Multiple myeloma (MM) is a currently incurable neoplasm of terminally differentiated B cells. The translocation and/or overexpression of c-MAF have been observed in human MM. Although c-MAF might function as an oncogene in human MM, there has been no report thus far describing the direct induction of MM by c-MAF overexpression in vivo. In this study, we have generated transgenic (TG) mice that express c-Maf specifically in the B-cell compartment. Aged c-Maf TG mice developed B-cell lymphomas with some clinical features that resembled those of MM, namely, plasma cell expansion and hyperglobulinemia. Quantitative RT-PCR analysis demonstrated that Ccnd2 and Itgb7, which are known target genes of c-Maf, were highly expressed in the lymphoma cells. This novel TG mouse model of the human MM t(14;16)(q32;q23) chromosomal translocation should serve to provide new insight into the role of c-MAF in tumorigenesis.

The underrecognized progressive nature of N370S Gaucher disease and assessment of cancer risk in 403 patients.

Mutations in GBA1 gene that encodes lysosomal glucocerebrosidase result in Type 1 Gaucher Disease (GD), the commonest lysosomal storage disorder; the most prevalent disease mutation is N370S. We investigated the heterogeneity and natural course of N370S GD in 403 patients. Demographic, clinical, and genetic characteristics of GD at presentation were examined in a cross-sectional study. In addition, the relative risk (RR) of cancer in patients compared with age-, sex-, and ethnic-group adjusted national rates of cancer was determined. Of the 403 patients, 54% of patients were homozygous (N370S/N370S) and 46% were compound heterozygous for the N370S mutation (N370S/other). The majority of N370S/N370S patients displayed a phenotype characterized by late onset, predominantly skeletal disease, whereas the majority of N370S/other patients displayed early onset, predominantly visceral/hematologic disease, P < 0.0001. There was a striking increase in lifetime risk of multiple myeloma in the entire cohort (RR 25, 95% CI 9.17-54.40), mostly confined to N370S homozygous patients. The risk of other hematologic malignancies (RR 3.45, 95% CI 1.49-6.79), and overall cancer risk (RR 1.80, 95% CI 1.32-2.40) was increased. Homozygous N370S GD leads to adult-onset progressive skeletal disease with relative sparing of the viscera, a strikingly high risk of multiple myeloma, and an increased risk of other cancers. High incidence of gammopathy suggests an important role of the adaptive immune system in the development of GD. Adult patients with GD should be monitored for skeletal disease and cancers including multiple myeloma.

Molecular characterization of patients with X-linked Hyper-IgM syndrome: description of two novel CD40L mutations.

Type 1, X-linked Hyper-IgM syndrome (HIGM1) is caused by mutations in the gene encoding the CD154 protein, also known as CD40 ligand (CD40LG). CD40L is expressed in activated T cells and interacts with CD40 receptor expressed on B lymphocytes and dendritic cells. Affected patients present cellular and humoral immune defects, with infections by intracellular, opportunistic and extracellular pathogens. In the present study we investigated the molecular defects underlying disease in four patients with HIGM1. We identified four distinct CD40L mutations, two of them which have not been previously described. P1 harboured the novel p.G227X mutation which abolished CD40L expression. P2 had a previously described frame shift deletion in exon 2 (p.I53fsX65) which also prevented protein expression. P3 demonstrated the previously known p.V126D change in exon 4, affecting the TNF homology (TNFH) domain. Finally, P4 evidenced the novel p.F229L mutation also located in the TNFH domain. In silico analysis of F229L predicted the change to be pathological, affecting the many hydrophobic interactions of this residue. Precise molecular diagnosis in HIGM syndrome allows reliable detection of carriers, making genetic counselling and prenatal diagnosis possible.

Ocular adnexal IgG4-related disease has uniform clinicopathology.

IgG4-related disease is a recently proposed clinical entity with several unique clinicopathological features. Ocular adnexal IgG4-related disease, however, has not well been clarified. The purpose of the present study was to examine 21 patients (10 men, 11 women; age range, 39-86 years) with ocular adnexal IgG4-related disease. In 17 out of 21 patients (81%), the lacrimal glands were involved and bilateral lacrimal gland swelling was frequently observed (n = 12; 70.6%). In contrast, the conjunctiva was not involved in any of the patient. Histology was uniform with marked lymphoplasmacytic infiltration admixed with dense fibrosis, similar to previous reports of IgG4-related disease. Immunostaining detected numerous aggregates of IgG4-positive plasma cells. Serum IgG4 was higher than normal in 10 of the 13 patients tested, although it was measured after treatment in almost all cases. Interestingly, immunoglobulin heavy chain gene rearrangement was detected in two of 17 patients (12%) examined. The present results show that ocular adnexal IgG4-related disease has uniform clinicopathology: that is, disease involving the bilateral lacrimal glands with lymphoid hyperplasia and fibrosis, but not the conjunctiva. And presence of immunoglobulin heavy chain gene rearrangement suggests the possibility of B-cell lymphoma arising in a background of IgG4-related chronic inflammation.

The effect of activating and inhibiting Fc-receptors on murine mercury-induced autoimmunity.

Fc-receptors for IgG (FcgammaR) link cellular and humoral immune responses, controlling the balance between activating and inhibitory immune responses, and are involved in autoimmune diseases. Mercury (Hg) induces an autoimmune condition in genetically (H-2(s,q,f)) susceptible mice characterized by lymphoproliferation, hypergammaglobulinemia and IgG antinucleolar antibodies (ANoA). Here we investigate the role of activating (FcgammaRI, FcgammaRIII) and inhibitory (FcgammaRIIb) Fc-receptors on mercury-induced autoimmunity (HgIA) using DBA/1 mice (H-2(q)) with targeted FcgammaR mutations and wild type (wt) mice. Mice deficient for the FcRgamma-chain or FcgammaRIII and treated with 15 mg/L HgCl(2) showed a delayed and attenuated IgG1, IgG2a and IgG2b ANoA response compared to wt mice. Female Hg-treated FcgammaRIIB(-/-) mice showed a significant increased of IgG2b ANoA development compared to wt mice. The total serum IgG1 response due to Hg was attenuated in FcRgamma(-/-) and FcgammaRIII(-/-) mice compared to wt mice. Hg-treated FcgammaRIIB(-/-) mice showed an increase of both serum IgG1 and IgE compared to wt mice. We conclude that FcgammaRIII is of importance for the rapidity and final strength of the ANoA response and the increase in serum IgG1 in HgIA, while lack of FcgammaRIIb increases the IgG2b ANoA response and the serum IgG1 and IgE response.

Introduction of a CD40L genomic fragment via a human artificial chromosome vector permits cell-type-specific gene expression and induces immunoglobulin secretion.

Gene therapy using cDNA driven by an exogenous promoter is not suited for genetic disorders that require intrinsic expression of a transgene, such as hyperimmunoglobulin (Ig)M syndrome (HIGM), which is caused by mutations in the CD40L gene. The human artificial chromosome (HAC) vector has the potential to solve this problem, because it can be used to transfer large genomic fragments containing their own regulatory elements. In this study, we examined whether introduction of a genomic fragment of CD40L via the HAC vector permits intrinsic expression of the transgene and has an effect on immunoglobulin secretion. We constructed an HAC vector carrying the mouse CD40L genomic fragment (mCD40L-HAC) in Chinese hamster ovary (CHO) cells and transferred the mCD40L-HAC vector into a human CD4-positive active T-cell line (Jurkat) and a human myeloid cell line (U937) via microcell-mediated chromosome transfer (MMCT). The mCD40L-HAC vector permits mCD40L expression in human active T cells but not in human myeloid cells. The mCD40L-HAC also functions to stimulate mouse B cells derived from CD40L(-/-) mice, inducing secretion of IgG. This study may be an initial step toward the therapeutic application of HAC vectors for intrinsic expression of genes, a potential new direction for genome-based gene therapy.