Human cytomegalovirus infection downregulates expression of the cellular aminopeptidases CD10 and CD13

Dengue Virus Increases the Expression of TREM-1 and CD10 on Human Neutrophils

Every year, dengue is responsible for 400 million infections worldwide. Inflammation is related to the development of severe forms of dengue. Neutrophils are a heterogeneous cell population with a key role in the immune response. During viral infection, neutrophils are mainly recruited to the infection site; however, their excessive activation is linked to deleterious results. During dengue infection, neutrophils are involved in the pathogenesis through neutrophils extracellular traps production, tumor necrosis factor-alpha, and interleukin-8 secretion. However, other molecules regulate the neutrophil role during viral infection. TREM-1 is expressed on neutrophils and its activation is related to increased production of inflammatory mediators. CD10 is expressed on mature neutrophils and has been associated with the regulation of neutrophil migration and immunosuppression. However, the role of both molecules during viral infection is limited, particularly during dengue infection. Here, we report for the first time that DENV-2 can significantly increase TREM-1 and CD10 expression as well as sTREM-1 production in cultured human neutrophils. Furthermore, we observed that treatment with granulocyte-macrophage colony stimulating factor, a molecule mostly produced in severe cases of dengue, is capable of inducing the overexpression of TREM-1 and CD10 on human neutrophils. These results suggest the participation of neutrophil CD10 and TREM-1 in the pathogenesis of dengue infection.

Poly(I:C) promotes neurotoxic amyloid β accumulation through reduced degradation by decreasing neprilysin protein levels in astrocytes

Inflammation associated with viral infection of the nervous system has been involved in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease (AD) and multiple sclerosis. Polyinosinic:polycytidylic acid (poly[I:C]) is a Toll-like receptor 3 (TLR3) agonist that mimics the inflammatory response to systemic viral infections. Despite growing recognition of the role of glial cells in AD pathology, their involvement in the accumulation and clearance of amyloid β (Aβ) in the brain of patients with AD is poorly understood. Neprilysin (NEP) and insulin-degrading enzyme (IDE) are the main Aβ-degrading enzymes in the brain. This study investigated whether poly(I:C) regulated Aβ degradation and neurotoxicity by modulating NEP and IDE protein levels through TLR3 in astrocytes. To this aim, primary rat primary astrocyte cultures were treated with poly(I:C) and inhibitors of the TLR3 signaling. Protein levels were assessed by Western blot. Aβ toxicity to primary neurons was measured by lactate dehydrogenase release. Poly(I:C) induced a significant decrease in NEP levels on the membrane of astrocytes as well as in the culture medium. The degradation of exogenous Aβ was markedly delayed in poly(I:C)-treated astrocytes. This delay significantly increased the neurotoxicity of exogenous Aβ1-42. Altogether, these results suggest that viral infections induce Aβ neurotoxicity by decreasing NEP levels in astrocytes and consequently preventing Aβ degradation.

Quantitative temporal viromics: an approach to investigate host-pathogen interaction

A systematic quantitative analysis of temporal changes in host and viral proteins throughout the course of a productive infection could provide dynamic insights into virus-host interaction. We developed a proteomic technique called “quantitative temporal viromics” (QTV), which employs multiplexed tandem-mass-tag-based mass spectrometry. Human cytomegalovirus (HCMV) is not only an important pathogen but a paradigm of viral immune evasion. QTV detailed how HCMV orchestrates the expression of >8,000 cellular proteins, including 1,200 cell-surface proteins to manipulate signaling pathways and counterintrinsic, innate, and adaptive immune defenses. QTV predicted natural killer and T cell ligands, as well as 29 viral proteins present at the cell surface, potential therapeutic targets. Temporal profiles of >80% of HCMV canonical genes and 14 noncanonical HCMV open reading frames were defined. QTV is a powerful method that can yield important insights into viral infection and is applicable to any virus with a robust in vitro model.

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>8,000 proteins quantified over eight time points, including 1,200 cell-surface proteins

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Temporal profiles of 139/171 canonical HCMV proteins and 14 noncanonical HCMV ORFs

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Multiple families of cell-surface receptors selectively modulated by HCMV

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Multiple signaling pathways modulated during HCMV infection

NF-kappaB down-regulates expression of the B-lymphoma marker CD10 through a miR-155/PU.1 pathway

Cell-surface protein CD10 is a prognostic marker for diffuse large B-cell lymphoma (DLBCL), where high expression of CD10 is found in the germinal center B-cell (GCB) subtype and CD10 expression is low or absent in the activated B-cell (ABC) subtype. As compared with the GCB subtype, patients with ABC DLBCL have a poorer prognosis after standard treatment, and ABC tumor cells have higher NF-κB activity. Herein, we show that increased expression of the NF-κB target micro-RNA miR-155 is correlated with reduced expression of transcription factor PU.1 and CD10 in several B-lymphoma cell lines. Moreover, electromobility shift assays and luciferase reporter assays indicate that PU.1 can directly activate expression from the CD10 promoter. Expression of a DLBCL-derived mutant of the adaptor CARD11 (a constitutive activator of NF-κB) in the GCB-like human BJAB cell line or v-Rel in the chicken DT40 B-lymphoma cell line causes reduced expression of PU.1. The CARD11 mutant also causes a decrease in CD10 levels in BJAB cells. Similarly, overexpression of miR-155, which is known to down-regulate PU.1, leads to reduced expression of CD10 in BJAB cells. Finally, we show that CD10 expression is reduced in BJAB cells after treatment with the NF-κB inducer lipopolysaccharide (LPS). Additionally, miR-155 is induced by LPS treatment or expression of the CARD11 mutant in BJAB cells. These results point to an NF-κB-dependent mechanism for down-regulation of CD10 in B-cell lymphoma: namely, that increased NF-κB activity leads to increased miR-155, which results in decreased PU.1, and consequently reduced CD10 mRNA and protein.

hDectin-1 is involved in uptake and cross-presentation of cellular antigens

Human Dectin-1 (hDectin-1) is a member of the C-type lectin-like receptor family that was shown to be the major receptor for fungal beta-glucans and to play an important role in the cellular responses mediated by these carbohydrates. In this study, we demonstrate that hDectin-1 is involved in the uptake and cross-presentation of cellular antigens. Furthermore, activation of monocyte-derived dendritic cells (MDCs) with toll-like receptor 3 (TLR3) ligand but not with TLR2 ligand or TLR7 ligand resulted in down-regulation of hDectin-1 expression and reduced phagocytosis of apoptotic tumor cells as well as presentation of pp65-derived T-cell epitopes upon engulfment of cytomegalovirus (CMV)-infected human foreskin fibroblasts.

Cytomegalovirus destruction of focal adhesions revealed in a high-throughput Western blot analysis of cellular protein expression

Human cytomegalovirus (HCMV) systematically manages the expression of cellular functions, rather than exerting the global shutoff of host cell protein synthesis commonly observed with other herpesviruses during the lytic cycle. While microarray technology has provided remarkable insights into viral control of the cellular transcriptome, HCMV is known to encode multiple mechanisms for posttranscriptional and post-translation regulation of cellular gene expression. High-throughput Western blotting (BD Biosciences Powerblot technology) with 1,009 characterized antibodies was therefore used to analyze and compare the effects of infection with attenuated high-passage strain AD169 and virulent low-passage strain Toledo at 72 hpi across gels run in triplicate for each sample. Six hundred ninety-four proteins gave a positive signal in the screen, of which 68 from strain AD169 and 71 from strain Toledo were defined as being either positively or negatively regulated by infection with the highest level of confidence (BD parameters). In follow-up analyses, a subset of proteins was selected on the basis of the magnitude of the observed effect or their potential to contribute to defense against immune recognition. In analyses performed at 24, 72, and 144 hpi, connexin 43 was efficiently downregulated during HCMV infection, implying a breakdown of intercellular communication. Mitosis-associated protein Eg-5 was found to be differentially upregulated in the AD169 and Toledo strains of HCMV. Focal adhesions link the actin cytoskeleton to the extracellular matrix and have key roles in initiating signaling pathways and substrate adhesion and regulating cell migration. HCMV suppressed expression of the focal-adhesion-associated proteins Hic-5, paxillin, and alpha-actinin. Focal adhesions were clearly disrupted in HCMV-infected fibroblasts, with their associated intracellular and extracellular proteins being dispersed. Powerblot shows potential for rapid screening of the cellular proteome during HCMV infection.

TLR ligands differentially affect uptake and presentation of cellular antigens

Dendritic cells (DCs) have the unique ability to efficiently present T-cell epitopes from exogenous antigens on MHC class I molecules, a process called cross-presentation. In our study we demonstrate that stimulation of monocyte-derived DCs with Toll-like receptor (TLR) ligands differentially affects the uptake and cross-presentation of cellular antigens. Activation of DCs with TLR3 or TLR4 but not with TLR2 or TLR7/8 ligands inhibited phagocytosis of apoptotic tumor cells and resulted in a reduced cross-presentation of pp65-derived T-cell epitopes on MHC class I molecules upon engulfment of cytomegalovirus (CMV)–infected fibroblasts. These results have an important impact on the understanding of the interactions between the immune system and pathogens and the development of vaccination strategies to treat malignant diseases.

Cytokine profile in response to Cytomegalovirus associated with immune recovery syndrome after highly active antiretroviral therapy

BACKGROUND

Several changes have occurred in the presentation and course of cytomegalovirus (CMV) retinitis in patients with AIDS since the introduction of HAART (highly active antiretroviral therapy). In some individuals who take HAART, retinitis is kept under control even after the discontinuation of anti-CMV therapy. However, many of these patients develop intraocular inflammation. Uveitis, cataract, vitreitis, cystoid macular edema, epiretinal membrane, and disc edema may occur in patients with immune recovery syndrome (IRS).

METHODS

We evaluated the CMV-specific immune response in 55 patients by assessing CMV-specific lymphocyte proliferation, cytotoxicity, and cytokine production and correlated it with the clinical outcome.

RESULTS

Our data suggest that control of CMV retinitis is associated with acquisition of cytotoxic and lymphoproliferative responses to CMV. In addition, the upsurge of macular and disc edema seems associated with the production of interleukin-4 and tumor necrosis factor-alpha, whereas vitreitis is associated with the production of interleukin-2 and interferon-gamma.

INTERPRETATION

The type of T-cell response that develops after HAART may determine the side effects of immune recovery and these effects are predictable based on the lymphokine profile produced by CMV-specific cells.

CD13/aminopeptidase N and murine cytomegalovirus infection

CD13/aminopeptidase N is a membrane-bound metalloproteinase implicated in human cytomegalovirus (HCMV) infection and pathogenesis. Anti-CD13 antibodies can neutralize HCMV infectivity, and HCMV viremia after bone marrow transplantation induces anti-CD13 autoantibodies which correlate with development of chronic graft vs. host disease. We examined whether murine CD13/APN was similarly implicated in murine cytomegalovirus (MCMV) disease. MCMV infection did induce anti-CD13 antibodies in mice in a strain-specific manner. ICR and 129S mice developed high titers of anti-CD13 antibodies and anti-MCMV antibodies after MCMV infection, whereas CBA and CBAxC57BL/6 f1 hybrid mice produced antibodies against MCMV only. Unlike HCMV, no evidence was found for a correlation between host cell CD13/APN expression and infection, or for the presence of CD13/APN on MCMV particles, although APN inhibitors decreased MCMV plaque formation. Reproduction of CD13/APN autoantibody production in the murine system should make it possible to determine if these antibodies contribute to CMV pathogenesis.

Identification of genes differentially expressed in Atlantic salmon (Salmo salar) in response to infection by Aeromonas salmonicida using cDNA microarray technology

The response of Atlantic salmon, Salmo salar, to infection by the bacterial pathogen Aeromonas salmonicida (the causative agent of furunculosis), was investigated using a cohabitation model and a custom Atlantic salmon cDNA microarray consisting of over 4000 different amplicons. Pooled samples of each of three immune-relevant tissues (spleen, head kidney and liver) were obtained from fish exposed to infected salmon for 13 days. Reverse transcription-PCR assays were used to verify the differential expression of 12 candidate genes uncovered by microarray analysis. Among the differentially expressed genes were several previously revealed by suppression subtractive hybridization and EST surveys and that are recognized to encode humoral components of the innate immune system. Other genes identified in this study were not previously associated with infection. In addition, a number of genes with no known homologs were uncovered. Determination of their specific roles during infection may lead to a better understanding of innate immunity.

Downregulation of the cellular adhesion molecule Thy-1 (CD90) by cytomegalovirus infection of human fibroblasts

The deregulation of cellular adhesion molecules by human cytomegalovirus (HCMV) appears to be correlated with the development of vascular disease. In this study, it was investigated whether the expression of Thy-1 (CD90), a member of the immunoglobulin superfamily of adhesion molecules with constitutive expression on fibroblast cells, is modulated following infection with HCMV. It was observed that Thy-1 cell surface expression decreased significantly during the course of infection. Addition of neutralizing antibodies, as well as UV inactivation of virus, prevented Thy-1 downregulation. In contrast, inhibition of virus replication by cidofovir did not alter Thy-1 regulation by HCMV, indicating that immediate-early (IE) and/or early (E) gene products are responsible. Interestingly, after infection of fibroblasts with a recombinant GFP-expressing virus, infected as well as non-infected cells showed a reduced Thy-1 cell surface expression. From these findings, it is concluded that IE or E gene products of HCMV induce a so far unidentified soluble factor that mediates Thy-1 downregulation.

The most abundantly transcribed human cytomegalovirus gene (beta 2.7) is non-essential for growth in vitro

The most abundantly transcribed HCMV gene (beta 2.7) encodes a 2.7 kb polyadenylated RNA. Although the laboratory-adapted HCMV strains AD169 and Towne possess two copies of the beta 2.7 gene within an expanded b sequence element, the low passage strain Toledo and all clinical isolates analysed contain only a single copy located within the U(L) region. A beta 2.7 deletion mutant constructed based on a strain Toledo background was shown to replicate with kinetics comparable to those of the parental virus; the beta2.7 gene is therefore not essential for virus replication in vitro. Sequencing the beta 2.7 gene from HCMV clinical isolates and the Toledo strain reveals that although the overall gene sequence is highly conserved (>99 %), the RL4 frame originally assigned in strain AD169 was disrupted in each of these viruses. Consequently, the beta 2.7 transcript does not encode any obvious translation product and thus may not function as an mRNA.

Human cytomegalovirus infection inhibits tumor necrosis factor alpha (TNF-alpha) signaling by targeting the 55-kilodalton TNF-alpha receptor

Infection with human cytomegalovirus (HCMV) results in complex interactions between viral and cellular factors which perturb many cellular functions. HCMV is known to target the cell cycle, cellular transcription, and immunoregulation, and it is believed that this optimizes the cellular environment for viral DNA replication during productive infection or during carriage in the latently infected host. Here, we show that HCMV infection also prevents external signaling to the cell by disrupting the function of TNFRI, the 55-kDa receptor for tumor necrosis factor alpha (TNF-alpha), one of the receptors for a potent cytokine involved in eliciting a wide spectrum of cellular responses, including antiviral responses. HCMV infection of fully permissive differentiated monocytic cell lines and U373 cells resulted in a reduction in cell surface expression of TNFRI. The reduction appeared to be due to relocalization of TNFRI from the cell surface and was reflected in the elimination of TNF-alpha-induced Jun kinase activity. Analysis of specific phases of infection suggested that viral early gene products were responsible for this relocalization. However, a mutant HCMV in which all viral gene products known to be involved in down-regulation of major histocompatibility complex (MHC) class I were deleted still resulted in relocalization of TNFRI. Consequently, TNFRI relocalization by HCMV appears to be mediated by a novel viral early function not involved in down-regulation of cell surface MHC class I expression. We suggest that upon infection, HCMV isolates the cell from host-mediated signals, forcing the cell to respond only to virus-specific signals which optimize the cell for virus production and effect proviral responses from bystander cells.

Human cytomegalovirus infection inhibits epidermal growth factor (EGF) signalling by targeting EGF receptors

Infection with human cytomegalovirus (HCMV) is known to involve complex interactions between viral and cellular factors resulting in perturbation of a number of cellular functions. Specifically, HCMV infection targets control of the cell cycle, cellular transcription and immunoregulation, presumably to optimize the cellular environment for virus persistence and productive infection. Here, we show that HCMV infection also prevents external signalling to the cell by disrupting the function of epidermal growth factor receptor (EGFR). Infection with HCMV resulted in a decrease in cell-surface expression of EGFR. This decrease was correlated with a concomitant decrease in steady-state levels of EGFR protein. Consistent with this, HCMV inhibited EGF-mediated receptor autophosphorylation. Infection with a mutant HCMV deleted of all viral gene products known to be involved in down-regulation of MHC Class I receptors still resulted in this down-regulation, implying that EGFR down-regulation by HCMV is mediated by a novel virus function. We suggest that a primary goal of HCMV is to 'isolate' the infected cell from host-mediated signals so that the cell responds solely to an array of virus-specific signals which optimize the cell for virus production.

Molecular determinants of species specificity in the coronavirus receptor aminopeptidase N (CD13): influence of N-linked glycosylation

Aminopeptidase N (APN), a 150-kDa metalloprotease also called CD13, serves as a receptor for serologically related coronaviruses of humans (human coronavirus 229E [HCoV-229E]), pigs, and cats. These virus-receptor interactions can be highly species specific; for example, the human coronavirus can use human APN (hAPN) but not porcine APN (pAPN) as its cellular receptor, and porcine coronaviruses can use pAPN but not hAPN. Substitution of pAPN amino acids 283 to 290 into hAPN for the corresponding amino acids 288 to 295 introduced an N-glycosylation sequon at amino acids 291 to 293 that blocked HCoV-229E receptor activity of hAPN. Substitution of two amino acids that inserted an N-glycosylation site at amino acid 291 also resulted in a mutant hAPN that lacked receptor activity because it failed to bind HCoV-229E. Single amino acid revertants that removed this sequon at amino acids 291 to 293 but had one or five pAPN amino acid substitution(s) in this region all regained HCoV-229E binding and receptor activities. To determine if other N-linked glycosylation differences between hAPN, feline APN (fAPN), and pAPN account for receptor specificity of pig and cat coronaviruses, a mutant hAPN protein that, like fAPN and pAPN, lacked a glycosylation sequon at 818 to 820 was studied. This sequon is within the region that determines receptor activity for porcine and feline coronaviruses. Mutant hAPN lacking the sequon at amino acids 818 to 820 maintained HCoV-229E receptor activity but did not gain receptor activity for porcine or feline coronaviruses. Thus, certain differences in glycosylation between coronavirus receptors from different species are critical determinants in the species specificity of infection.

Human cytomegalovirus pp65- and immediate early 1 antigen-specific HLA class I-restricted cytotoxic T cell responses induced by cross-presentation of viral antigens

Dendritic cells (DCs) play a pivotal role in the development of anti-viral CD8(+) CTL responses. This is straightforward if they are directly infected with virus, but is less clear in response to viruses that cannot productively infect DCS: Human CMV (HCMV) shows strain-specific cell tropism: fibroblast (Fb)-adapted laboratory strains (AD169) and recent clinical isolates do not infect DCs, whereas endothelial cell-adapted strains (TB40/E) result in productive lytic DC infection. However, we show here that uninfected DCs induce CD8(+) T cell cytotoxicity and IFN-gamma production against HCMV pp65 and immediate early 1 Ags following in vitro coculture with HCMV-AD169-infected Fbs, regardless of the HLA type of these FBS: CD8(+) T cell stimulation was inhibited by pretreatment of DCs with cytochalasin B or brefeldin A, indicating a phagosome/endosome to cytosol pathway. HCMV-infected Fbs were not apoptotic as measured by annexin V binding, and induction of apoptosis of infected Fbs in vitro did not augment CTL induction by DCs, suggesting a mechanism other than apoptosis in the initiation of cross-presentation. Furthermore, HCMV-infected Fbs provided a maturation signal for immature DCs during coculture, as evidenced by increased CD83 and HLA class II expression. Cross-presentation of HCMV Ags by host DCs enables these professional APCs to bypass some of the evasion mechanisms HCMV has developed to avoid T cell recognition. It may also serve to explain the presence of immediate early 1 Ag-specific CTLs in the face of pp65-induced inhibition of Ag presentation at the level of the infected cell.

Immune evasion by human cytomegalovirus: lessons in immunology and cell biology

The human cytomegalovirus (HCMV) has dedicated a significant part of its genome to genes encoding molecules that modulate the host immune response. Many of these genes have homologues in the host genome. Others, however, are unique in the sense that no obvious primary sequence identity is found in the available databases. The HCMV gene products interfere with the activation of MHC class I and class II restricted T cells and NK cells, modify the function of cytokines and their receptors, interact with complement factors and modulate signal transduction and transcription factor activity, in addition to interference with many other cellular functions. Investigation of these evasion strategies has not only improved our understanding of HCMV pathogenesis, but has also provided unexpected, novel insights into basic cell biological and immunological processes.

A phase I-II trial to examine the toxicity of CMV- and EBV-specific cytotoxic T lymphocytes when used for prophylaxis against EBV and CMV disease in recipients of CD34-selected/T cell-depleted stem cell transplants

Epstein-Barr virus (EBV)-induced lymphoproliferative disease and cytomegalovirus (CMV) infection are major causes of morbidity and mortality in individuals with compromised cellular immunity. Although anti-viral pharmacological agents exist, severe side effects such as myelosuppression often limit the application of these medications. Infusion of ex vivo-expanded, virus-specific cytotoxic T-lymphocytes (CTL) has been proven to be safe and efficacious for the prophylaxis and treatment of EBV and CMV complications. While EBV-specific CTL can be readily and reliably produced with EBV-immortalized B-lymphoblastoid cell lines (BLCL) as stimulators, current protocols for CMV-specific CTL, which use CMV-infected fibroblasts as stimulators, may be associated with alloreactivity and the need for cloning, as well as the potential for exposure to human blood-born infectious agents. Our laboratory has developed a novel system to generate EBV/CMV-bi-specific CTL by co-culturing PBMC with autologous BLCL expressing a CMV protein pp65 (BLCLpp65) (Sun et al., 1999). pp65, an immunodominant CMV antigen, is transduced into BLCL by a recombinant retrovirus MSCVpp65. While low in alloreactivity, BLCLpp65-stimulated CTL are cytolytic to autologous cells infected with EBV or CMV, and this cytotoxicity is mediated by polyclonal, CD8+, MHC Class I-restricted T-cells. Further experiments revealed that retroviral transduction and expression of pp65 do not compromise the capacity of presenting EBV antigens, and T cells stimulated by BLCLpp65 recognize clinical strains of CMV (Sun et al., 2000). These data indicated that BLCLpp65 could substitute for BLCL as antigen presenting cells in adoptive immunotherapy against EBV-LPD, with the benefit of providing protection against CMV reactivation. This protocol is a Phase I/II study to examine the toxicity associated with and the immunologic effects of ex vivo simultaneously expanded EBV- and CMV-specific CTL for prophylaxis against EBV and CMV complications in recipients of CD34 selected/T-cell depleted stem cell transplants (SCT). EBV/CMV-specific CTL will be generated from peripheral blood mononuclear cells (PBMC) of EBV/CMV-seropositive donors in a course of from 21-28 days by weekly stimulation with autologous BLCLpp65. Qualified CTL will be administered to consenting patients at 40, 60, and 80 days post-transpOFF criteria of molecular virology and immunological reconstitution, which include blood levels of pp65 antigen and EBV viral DNA, and virus-specific CTL precursor frequency. Patients will also be tested for replication-competent retrovirus at 3, 6, and 12 month intervals post-transplant to ensure bio-safety.

Binding properties of a highly potent and selective iodinated aminopeptidase N inhibitor appropriate for radioautography

Aminopeptidase N (APN) is a zinc metallopeptidase involved in the inactivation of biologically active peptides. The knowledge of its precise distribution is crucial to investigate its physiological role. This requires the use of appropriate probes such as the recently developed highly potent and selective radiolabeled APN inhibitor 2(S)-benzyl-3-[hydroxy(1'(R)-aminoethyl)phosphinyl]propanoyl-L-3-[ (12 5)I]iodotyrosine ([(125)I]RB 129). Its binding properties were investigated using rat brain homogenates (K(d)=3.4 nM) or APN expressed in COS-7 cells (K(d)=0.9 nM). The specific binding was 95% at [K(d)], and preliminary autoradiography in intestine is promising. The decreased affinity of [(125)I]RB 129 (=10(-6) M) for the E(350)D APN mutant, supports the critical role of E(350) in the amino-exopeptidase action of APN.

CD10 positive thyroid marginal zone non-Hodgkin lymphoma

A 72 year old woman presented with swelling of the right lobe of her thyroid gland. Fine needle aspiration and flow cytometry showed a clonal population of B cells expressing CD10 and a diagnosis of follicle centre cell lymphoma was made. Subsequent excision of the thyroid showed the typical histological features of a marginal zone non-Hodgkin lymphoma. Polymerase chain reaction showed no evidence of t (14;18). Immunohistochemistry confirmed CD10 positivity and LN1 (CDw75) expression. This is only the second report of aberrant expression of CD 10 by a marginal zone lymphoma.