No description available.

Marginal zone lymphomas (MZLs) are a heterogeneous group of neoplasms that resemble the normal B-cell populations of the marginal zone of a lymph node. It includes three different subtypes, nodal, splenic, and extra -nodal, each, with overlapping features and yet unique characteristics. Nodal Marginal Zone lymphoma (NMZL) accounts for only 1% of all Non-Hodgkin Lymphoma (NHL). Marginal Zone lymphoma with plasmacytic differentiation is not very common. We report a unique case of Nodal marginal zone lymphoma initially presenting with lymphocytosis and lymphadenopathy, work up indicating low grade lymphoma, subsequently developing hyper viscosity syndrome due to symptomatic IgM monoclonal gammopathy. A 68 year old female was noted to have persistent leukocytosis with lymphocytic predominance after completing treatment for a urinary tract infection. Clinical exam revealed bilateral axillary adenopathy. CT scan of neck, chest, abdomen and pelvis revealed axillary, mediastinal and retroperitoneal adenopathy with splenomegaly. Chronic lymphocytic leukemia (CLL) was suspected and work up initiated. Peripheral blood Flow-cytometry revealed 24% small B-cells with surface kappa light chain restriction consistent with mature B-cell lymphoma or leukemia without typical immune phenotype of CLL. Lab reported significant elevation of total protein at 10 g/dl. Workup for para-proteinemia consistent with IgM level over 5000 mg/dl, with serum viscosity of 8. Axillary lymph node excisional biopsy reported marginal zone lymphoma with plasmacytic differentiation. Bone marrow biopsy demonstrated 42% monoclonal B-cells without co-expression of CD5 and CD23. FISH studies positive for duplication 1q and Molecular testing negative for MYDD88 mutation. Decision was made to initiate chemo therapy with R-CVP for a total of six cycles. Her treatment course was complicated by symptomatic hyper viscosity syndrome necessitating therapeutic plasmapheresis. Patient successfully completed chemo immunotherapy with normalization of blood counts, resolution of palpable adenopathy and splenomegaly. Nodal marginal lymphoma (NMZL) originates from nodal mono-cytoid or marginal zone B cells and the pathogenesis usually involves acquired mutations in oncogenes and tumor suppressor genes involving MLL2, PTTPRD, NOTCH2, and KLF2 genes. The median age is round 70 years with slight male predominance. The clinical picture varies and usually includes generalized lymphadenopathy along with B symptoms and infrequently with mild monoclonal gammopathy (any immunoglobulin subtype-IgM uncommon). Marginal Zone lymphoma with plasmacytic differentiation is not as common and shares immuno-histochemical features with lympho-plasmacytic lymphoma (LPL). They both express B cell markers CD19, CD20, and CD22) and not CD5, CD10 or CD23. Clinically, NMZL is more likely to present with prominent lymphadenopathy, while LPL can exclusively affect the marrow without extramedullary involvement. IgM levels in NMZL tend to be lower than in LPL, typically lower than 1000 mg/d. MYD88 mutation is very common in LPL, and can be seen in 10-15% NMZL. The presence of IgM monoclonal gammopathy increases the serum viscosity which can lead to serious neurologic and ophthalmologic complications. Treatment involves emergent plasmapheresis. Our case highlights a less common NHL, presenting with significant paraproteinemia and developing hyper viscosity syndrome with impressive response to plasmapheresis and chemo immunotherapy.

Marginal zone B-cell lymphomas (MZBL) constitute 7% of all non-Hodgkin lymphomas, being the third most common subtype after diffuse large B-cell lymphoma(DLBCL) and follicular lymphoma. Extranodal MZBL (ENMZBL) most commonly arise from the mucosa-associated lymphoid tissue (MALT lymphoma), with stomach being the most common site. ENMZBL involving the dura is anatomically unusual and very rare. A 54 year old female presented to the hospital with worsening headaches and new onset generalized tonic clonic seizures. Complete blood counts and chemistry were unremarkable. No constitutional symptoms, new / progressive lymphadenopathy reported. Magnetic resonance Imaging( MRI) brain showed an enhancing right subdural soft tissue lesion overlying the right frontotemporal lobe suggestive of meningioma versus metastasis. Computed Tomography (CT) chest/abdomen/pelvis revealed no mass or lymphadenopathy. Lumbar Puncture cerebrospinal fluid cytology was negative for malignancy. She underwent brain biopsy. Pathology revealed diffuse infiltrate of small to medium-sized lymphoid cells, Immunohistochemical stains positive for CD 20, PAX5, CD 79a, Ki-67 at 5-10%, weakly positive for MUM1 and BCL2, negative for CD3, CD5, CD10, BCL6, cyclin D1, consistent with ENMZBL. Bone marrow biopsy and aspiration negative for involvement with lymphoma. Patient received local/regional therapy with radiation (XRT), total dose 24 Gy in 12 fractions. She presented six months later with worsening neck pain. MRI cervical spine revealed diffuse thick dural based enhancement within the spinal canal at C1-C4 levels leading to moderate-to-severe spinal canal stenosis at C2-C3 level with significant soft tissue extension. Repeat labs, systemic imaging, and bone marrow biopsy continued to show no evidence of systemic disease. She received low dose XRT to the entire craniospinal axis (dose-4Gy). Patient developed profound pancytopenia secondary to craniospinal XRT. After count recovery she initiated daily oral Ibrutinib (560 mg) with plans for a treatment duration of one year. Dural based ENMZL usually present as solitary masses, mimicking meningioma's. Marked female predilection is seen with median age of onset 50 years. Very few cases have been reported in literature with no standard therapy being described. ENMZL are usually indolent requiring less aggressive therapy. In contrast, primary CNS lymphoma (PCNSL) of diffuse large B cell histology is usually aggressive with high tendency to relapse, requiring treatment with high dose methotrexate based regimes. Dural based ENMZL therapy entails local treatments such as surgery and radiation therapy (relatively low dose radiation usually effective with prolonged durable responses). Systemic treatment with single agent Rituximab or with Tyrosine Kinase inhibitors like Ibrutinib with CNS penetration can also be considered. Long-term follow-up is recommended even in those patients who achieved complete remission as relapses may occur.

Classical immunoglobulin transgenic (Ig-Tg) mouse models such as the MD4 anti-hen egg lysozyme (-HEL) Ig-Tg line have been used extensively to study B cell responses in tolerance and immunity. This thesis describes a new generation of gene-targeted mice (designated SWHEL mice) whereby the VH10 Ig variable gene encoding the HyHEL-10 specificity of the original anti-HEL Ig-Tg mouse was targeted to the Ig heavy chain locus. B cells in the SWHEL mouse are therefore capable of undergoing class switch recombination (CSR) and somatic hypermutation (SHM), representing a major advance on the original MD4 mouse model. SWHEL mice were found to not only contain a large population of HEL-specific (HEL+) B cells but also a significant population of non-HEL-binding (HEL-) B cells generated by VH gene replacement. HEL+ SWHEL B cells were found to belong to the B2 lineage and displayed high levels of surface IgM. Nevertheless, they matured normally and colonised the primary B cell follicle and marginal zone (MZ) of the spleen. The SWHEL model thus provided an opportunity to re-examine some of the original observations made in the MD4 system and also to extend these observations, particularly with regard to the regulation of CSR by self-reactive B cells. As expected, analysis of SWHEL B cells exposed to high avidity membrane-bound HEL revealed that they underwent clonal deletion in the bone marrow (BM). More interestingly, analysis of HEL+ B cells exposed to low avidity soluble HEL revealed that they were able to emigrate from the BM to the spleen as anergic B cells. However, unlike anergic MD4 B cells, anergic SWHEL B cells were reduced in frequency, displayed an immature B cell phenotype, were excluded from the follicle and had a reduced lifespan. Direct measurement of B cell antigen receptor (BCR) occupancy by HEL and the frequency of HEL- competitor B cells was combined with mixed BM irradiation chimeras to demonstrate unequivocally that the difference in phenotype and fate of HEL+ B cells in the two systems was due solely to competition from HEL- B cells. In addition, the SWHEL model of B cell self-tolerance was used to show that while self-reactive B cells were hypo-responsive to BCR stimulation, BCR-independent signals delivered via anti-CD40 plus IL-4 or lipopolysaccharide could trigger them to undergo CSR and secretion of potentially pathogenic isotype-switched autoantibodies. Finally, the SWHEL model was used to study the responses of adoptively transferred follicular (Fo) and MZ B cells to in vivo activation with HEL conjugated to sheep red blood cells (HEL-SRBC). These studies revealed that both HEL+ MZ and Fo B cells were capable of mounting a robust T cell-dependent IgG1 antibody response to HEL-SRBC. However, HEL+ MZ B cells did not efficiently localise to the T cell-B cell border following antigen engagement and preferentially migrated to the bridging channels and red pulp. In contrast, HEL+ Fo B cells rapidly localised to the T cell-B cell border and subsequently colonised numerous germinal centres. As a result, the rate and pattern of SHM by HEL+ Fo and MZ B cells was shown to be distinct, with preferential targeting of mutations to the second complementarity-determining region in the former and to the second framework region in the latter. Together these data indicate illustrate the value of the SWHEL model and its potential to greatly advance the current understanding of B cell responses in tolerance and immunity.

B cell development is a highly organized process, which commences in the fetal liver during embryogenesis and in the bone marrow (BM) after birth. Surface IgM+ immature B cells emigrate from the BM via the blood stream to the spleen and finally differentiate into conventional mature follicular B (FoB) cells and marginal zone (MZ) B cells. Conversely, some sIgM+ immature B cells can also mature into IgD+ FoB cells in the BM. The ubiquitously expressed cell surface glycoprotein CD47 and its receptor signal regulatory protein α (SIRPα) are members of the immunoglobulin superfamily. Both individually and upon their interaction, CD47 and SIRPα have been found to play important role in the homeostasis of T lymphocytes or CD8­ conventional dendritic cells (cDCs) in secondary lymphoid organs. However, their role in regulating B cell homeostasis has remained unknown. The present study describes important roles of CD47 and SIRPα in B cell homeostasis. Lack of SIRPα signaling in adult SIRPα mutant (MT - cytoplasmic domain deletion) mice resulted in an impaired B cell maturation in the BM and spleen, which was also reflected in the blood. In the BM and spleen of SIRPα MT mice, reduced numbers of semi-mature IgD+IgMhi follicular type-II (F-II) and mature IgD+IgMlo follicular type-I (F-I) B cells were observed, while earlier BM B cell progenitors or splenic transitional B cells remained unaltered. In SIRPα MT mice, maturing B cells in BM and spleen were found to express higher levels of the pro-apoptotic protein BIM and contained an increased level of apoptotic cells. In contrast to that for FoB cells, the splenic MZ B cell population was increased with age in SIRPα MT mice without showing an increased level of activation markers. Immunohistochemical analysis revealed an increased follicular localization of MZ B cells in the spleens of SIRPα MT mice. In addition, MZ macrophages and marginal metallophilic macrophages were not restricted to their normal position in SIRPα MT spleens. Interestingly, CD47-deficient (CD47-/-) mice mimicked the FoB cell phenotype observed in SIRPα MT mice and had a reduced number of  FoB cells in the BM, blood and the spleen at 5­6 months of age, but not in younger mice. Similar to SIRPα MT mice, CD47-/- mice also displayed an increased number of splenic MZ B cells. Sera form both mouse strains did not show any signs of an increased production of autoantibodies or antinuclear antigens. BM reconstitution experiments identified a requirement for non-hematopoietic SIRPα signaling for normal B cell maturation in the BM and to maintain normal numbers and retention of MZ B cells in the splenic MZ. On the contrary, hematopoietic SIRPα signaling appeared to be important for FoB cell maturation in the spleen. Interestingly, hematopoietic SIRPα was required for normal MZ retention of MZ macrophages while normal distribution of metallophilic macrophages required non­hematopoietic SIRPα signaling.  Collectively, these findings revealed an important role of CD47 and of SIRPα signaling in B cell homeostasis in different lymphoid organs.

Classical immunoglobulin transgenic (Ig-Tg) mouse models such as the MD4 anti-hen egg lysozyme (-HEL) Ig-Tg line have been used extensively to study B cell responses in tolerance and immunity. This thesis describes a new generation of gene-targeted mice (designated SWHEL mice) whereby the VH10 Ig variable gene encoding the HyHEL-10 specificity of the original anti-HEL Ig-Tg mouse was targeted to the Ig heavy chain locus. B cells in the SWHEL mouse are therefore capable of undergoing class switch recombination (CSR) and somatic hypermutation (SHM), representing a major advance on the original MD4 mouse model. SWHEL mice were found to not only contain a large population of HEL-specific (HEL+) B cells but also a significant population of non-HEL-binding (HEL-) B cells generated by VH gene replacement. HEL+ SWHEL B cells were found to belong to the B2 lineage and displayed high levels of surface IgM. Nevertheless, they matured normally and colonised the primary B cell follicle and marginal zone (MZ) of the spleen. The SWHEL model thus provided an opportunity to re-examine some of the original observations made in the MD4 system and also to extend these observations, particularly with regard to the regulation of CSR by self-reactive B cells. As expected, analysis of SWHEL B cells exposed to high avidity membrane-bound HEL revealed that they underwent clonal deletion in the bone marrow (BM). More interestingly, analysis of HEL+ B cells exposed to low avidity soluble HEL revealed that they were able to emigrate from the BM to the spleen as anergic B cells. However, unlike anergic MD4 B cells, anergic SWHEL B cells were reduced in frequency, displayed an immature B cell phenotype, were excluded from the follicle and had a reduced lifespan. Direct measurement of B cell antigen receptor (BCR) occupancy by HEL and the frequency of HEL- competitor B cells was combined with mixed BM irradiation chimeras to demonstrate unequivocally that the difference in phenotype and fate of HEL+ B cells in the two systems was due solely to competition from HEL- B cells. In addition, the SWHEL model of B cell self-tolerance was used to show that while self-reactive B cells were hypo-responsive to BCR stimulation, BCR-independent signals delivered via anti-CD40 plus IL-4 or lipopolysaccharide could trigger them to undergo CSR and secretion of potentially pathogenic isotype-switched autoantibodies. Finally, the SWHEL model was used to study the responses of adoptively transferred follicular (Fo) and MZ B cells to in vivo activation with HEL conjugated to sheep red blood cells (HEL-SRBC). These studies revealed that both HEL+ MZ and Fo B cells were capable of mounting a robust T cell-dependent IgG1 antibody response to HEL-SRBC. However, HEL+ MZ B cells did not efficiently localise to the T cell-B cell border following antigen engagement and preferentially migrated to the bridging channels and red pulp. In contrast, HEL+ Fo B cells rapidly localised to the T cell-B cell border and subsequently colonised numerous germinal centres. As a result, the rate and pattern of SHM by HEL+ Fo and MZ B cells was shown to be distinct, with preferential targeting of mutations to the second complementarity-determining region in the former and to the second framework region in the latter. Together these data indicate illustrate the value of the SWHEL model and its potential to greatly advance the current understanding of B cell responses in tolerance and immunity.

La zone marginale de la rate apparaît comme un lieu stratégique de détection des antigènes et agents pathogènes véhiculés par le sang. Ces propriétés sont principalement liées à la présence de cellules appartenant au système immunitaire inné parmi lesquelles se trouvent des nombreuses cellules présentatrices d’antigènes (APC), comme les macrophages, les lymphocytes B de la zone marginale (MZB) ou encore les cellules dendritiques (DC). Ces cellules représentent une première ligne de défense contre les pathogènes véhiculés par le sang et sont importantes pour l’initiation des réponses immunes. Il a fortement était suggéré la localisation dans la zone marginale d’une autre population appartenant au système immunitaire inné : les lymphocytes T Natural Killer invariants ou iNKT. Ces lymphocytes T non conventionnels sont caractérisés par l’expression de marqueurs de cellules NK et de lymphocytes T conventionnels notamment le TCR. Contrairement aux lymphocytes T conventionnels, les iNKT reconnaissent des antigènes (Ag) lipidiques (d’origine exogène ou endogène) présentés par l’intermédiaire de la molécule CD1d exprimée à la surface des APC, notamment les DC. En réponse à ces lipides, et notamment l’α-galactosylceramide (α-GalCer), les cellules iNKT ont la capacité unique de sécréter rapidement de grandes quantités de cytokines immunomodulatrices comme l’IFN-γ et/ou l’IL-4 qui, en retour, permettent l’activation d’autres populations immunes telles que les DC, les cellules NK, les lymphocytes B et lymphocytes T conventionnels. Les DC, en tant qu’APC professionnelles, sont de puissantes cellules activatrices des lymphocytes T conventionnels mais également des iNKT. Cependant, bien que souvent souligné dans la littérature, le rôle des autres APC dans l’activation des lymphocytes T conventionnels mais surtout des iNKT restait relativement obscur lorsque ce travail de thèse a débuté. Parmi les APC, les MZB représentaient des cibles idéales puisqu’elles ont la particularité d’exprimer fortement les molécules de présentation telle que les molécules du CMH de classe II, la molécule CD1d mais aussi les molécules de co-stimulation. Nous avons donc débuté notre travail par l’étude du rôle des MZB dans l’activation des lymphocytes conventionnels et des iNKT. Nous montrons que les MZB sensibilisés avec un peptide de l’ovalbumine sont capables d’activer les lymphocytes T CD4+, dont la réponse est orientée vers un profil Th1 après l’activation des MZB par le CpG-ODN (agoniste du TLR-9). Ainsi, les MZB se comportent comme de véritables APC. Nous avons ensuite étudié l’activation des iNKT en réponse à lα’-GalCer. De façon surprenante, bien que les MZB expriment fortement la molécule CD1d, elles sont incapables d’activer in vitro les iNKT primaires en réponse l’α-GalCer libre. Elles sont cependant capables de présenter l’α-GalCer aux iNKT suggérant qu’il manque aux MZB des facteurs (solubles ou non) pour induire l’activation des iNKT. De façon intéressante, l’ajout de DC non sensibilisées restaure la production d’IFN-γ et d’IL-4 par les iNKT co-cultivés en présence de MZB sensibilisés avec l’α-GalCer. Nous montrons que les DC participent à cette activation via un mécanisme de présentation croisée mais également via l’apport de facteurs nécessaires aux MZB pour induire l’activation des iNKT. Il existe une réelle coopération entre ces deux types d’APC pour une activation optimale des iNKT. Finalement, nous montrons que les MZB sensibilisés avec l’α-GalCer induisent l’activation des lymphocytes iNKT et NK in vivo. Nous nous sommes ensuite concentrés sur les DC qui comme indiqué ci-dessus, sont des APC professionnelles. Cependant, dans la rate, les DC représentent une population très hétérogène dont le rôle de chaque sous-population notamment dans l’activation des iNKT était également très peu connu lorsque ce travail a débuté. / The spleen, with its highly specialized lymphoid compartments, plays a central role in clearing blood-borne pathogens. Innate immune cells, that are mainly present in the marginal zone of the spleen, are strategically located to respond to blood-borne microorganisms and viruses. Among innate cells, macrophages and marginal zone B (MZB) cells represent the first line of defense against blood-borne pathogens and with dendritic cells (DC) are important for initiation of the immune response. Along with these populations of antigen-presenting cells (APC), it was also suggested that invariant Natural Killer T (iNKT), a population of innate-like T lymphocytes, were also located in the marginal zone of the spleen. Unlike conventional T lymphocytes, iNKT cells recognize exogenous and self (glyco)lipid antigens (Ag) presented by the non-classical class I Ag presenting molecule CD1d expressed on APC, in particular DC. Upon lipid recognition, in particular in response to the non-mammalian glycolipid, α-galactosylceramide (α-GalCer), iNKT cells have the unique capacity to rapidly produce large amounts of immunoregulatory cytokines, including IFN-γ and IL-4, which lead to downstream activation of other immune populations (DC, NK cells, B cells and conventional T cells). Through this property, iNKT cells influence the strength and quality of the ensuing immune response. Dendritic cells, as professional APC, are potent activators of conventional T lymphocytes and iNKT cells. When we started our PhD, the role of APC other than DC in the priming of T lymphocytes including iNKT cells remained unclear. Among them, MZB cells represented good candidates since they express high levels of MHC class II and CD1d molecules and their ability to activate and orientate conventional and innate-like T lymphocytes, such as iNKT cells, were elusive. We show that MZB cells, when loaded OVA peptide promote the release of IFN-γ and IL-4 by antigen specific CD4+ T lymphocytes and their stimulation with CpG-ODN biases them toward more Th1 inducers. Surprisingly, although able to activate iNKT hybridomas, MZB cells sensitized with free α-GalCer do not directly activate ex vivo sorted iNKT cells unless DC are added to the culture system. Dendritic cells help MZB cells to promote iNKT cell activation in part through α-GalCer cross-presentation and also through DC-expressed co-factors. Interestingly, MZB cells amplify the DC-mediated activation of iNKT cells and depletion of MZB cells from total splenocytes strongly reduces iNKT cell activation in response to α-GalCer. Thus, DC and MZB cells provide help to each other to optimize iNKT cell stimulation. Finally, in vivo transfer of α-GalCer-loaded MZB cells potently activates iNKT and NK cells. Thus, we show for the first time a role of MZB cell in iNKT cell activation in response to free α-GalCer, an important finding to better understand the modalities of iNKT cell activation. As mentioned above, DC are professional APC and thus are strong activators of conventional and unconventional T lymphocytes. However, DC in the spleen represent an heterogeneous cell population and when we started our study, the role of DC subsets in T lymphocyte priming was still unclear. Among DC subsets, we concentrated on the major splenic DC subset located in the marginal zone, the CD8α- DC. This DC subset was further subdivided in CD4+ and CD4- subtypes. We provide evidences that CD4+ and CD4- DC are equally efficient at priming CD4+ T lymphocytes when loaded with OVA peptide and whole OVA, leading to a mixed Th1/Th2 response, and also CD8+ T lymphocytes when pulsed with OVA peptide (but not whole OVA).

No description available.

Submitted by Helmut Patrocinio (hell.kenn@gmail.com) on 2017-11-10T16:29:31Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Marcos_Romualdo_Costa_TESE.pdf: 3272089 bytes, checksum: aaf244c49f569e8c070d41f2727a24c6 (MD5) / Approved for entry into archive by Ismael Pereira (ismael@neuro.ufrn.br) on 2017-11-10T17:31:16Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Marcos_Romualdo_Costa_TESE.pdf: 3272089 bytes, checksum: aaf244c49f569e8c070d41f2727a24c6 (MD5) / Made available in DSpace on 2017-11-10T17:31:31Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Marcos_Romualdo_Costa_TESE.pdf: 3272089 bytes, checksum: aaf244c49f569e8c070d41f2727a24c6 (MD5) Previous issue date: 2006 / Ao longo do desenvolvimento, as c?lulas neuroepiteliais do telenc?falo dividemse originando progenitores respons?veis pela gera??o sequencial dos diferentes tipos de neur?nios, astr?citos e oligodendr?citos do c?rtex cerebral. At? o presente, os progenitores telencef?licos estariam localizados nas zonas ventricular (ZV) e subventricular (ZSV). Sua posi??o ao longo dos eixos dorsoventral e rostro-caudal ? relacionada com territ?rios g?nicos e tipos celulares espec?ficos. Desta forma, observa-se a gera??o de neur?nios corticais glutamat?rgicos ou GABA?rgicos na ZV e ZSV do telenc?falo dorsal e ventral de roedores, respectivamente. Neste trabalho investigamos o potencial proliferativo in vivo e in vitro da zona marginal (ZM), conhecida por possuir neur?nios migrat?rios e diferenciados durante a corticog?nese. Determinamos o fen?tipo de c?lulas proliferativas da ZM e atrav?s de an?lise clonal utilizando infec??o por retrovirus contendo o gene para GFP (prote?na flourescente verde) acompanhamos as linhagens derivadas destes progenitores in vitro. C?lulas proliferativas in vivo foram marcadas atrav?s da administra??o do BrdU (bromodeoxiuridina, marcador da fase S do ciclo celular), combinada a ensaios imunohistoqu?micos para a identifica??o deste ant?geno e da forma fosforilada da histona 3 (expressa no final da fase G2 e durante a fase M do ciclo celular). Identificamos c?lulas proliferativas na ZM de camundongos a partir do dia embrinon?rio 14 (E14 - logo ap?s a divis?o da pr?-placa quando a ZM se torna distingu?vel) e por toda a corticog?nese com um aumento na proporc?o de c?lulas proliferativas de ~tr?s vezes em E18. As c?lulas proliferativas na ZM n?o expressam Pax6 ou Tbr2, fatores transcricionais caracter?sticos dos precursores da ZV e ZSV respectivamente. Ao longo da corticog?nese, esta popula??o precursora apresenta um padr?o de express?o do fator transcricional Olig2 seguindo um gradiente l?tero-medial, de modo que no per?odo perinatal todas as c?lulas proliferativas na zona marginal expressam o gene olig2. A an?lise das linhagens clonais geradas a partir destes precursores revelou um elevado potencial gliog?nico (~70% de clones gliais puros) quando comparado a ZV /ZSV (3,3%). Al?m disso, a ZM apresentou um significativo potencial neurog?nico, originando cerca de 30% de clones contendo neur?nios. Mostramos que os clones gliais puros da ZM s?o significativamente maiores que os da ZV. Conclu?mos, portanto, que a ZM dorsal ? um nicho neurog?nico e gliog?nico no c?rtex cerebral em desenvolvimento apresentando c?lulas proliferativas in vivo e in vitro com caracter?sticas fenot?picas distintas dos progenitores da ZV e ZSV. Atrav?s de estudos de linhagem clonal in vitro, demonstramos diferentes comportamentos proliferativos e potenciais neuro-gliog?nicos das c?lulas isoladas da ZM e da ZV/ZSV, indicando a exist?ncia de um novo tipo de progenitor no telenc?falo. / During development, telencephalic neuroepithelial cells proliferate and give rise to progenitors, which are responsible for the sequential generation of different types of neurons, astrocytes and oligodendrocytes in the cerebral cortex. To date, telencephalic progenitors would be located in the ventricular (VZ) and subventricular (SVZ) zones. Their position along the rostro-caudal and dorsoventral axis is related to gene expression territories and the generation of specific cell types, such that dorsal telencephalic VZ/ZVZ generates glutamatergic neurons and ventral VZ/ZVZ GABAergic neurons. In this work we investigated the in vivo and in vitro proliferative potential of the marginal zone (MZ) described to harbor migrating and differentiating neurons during corticogenesis. We determined the phenotype of MZ proliferative cells and by clonal analysis with infection by GFP (green fluorescent protein) containing retroviruses we followed the lineages derived from the progenitors in vitro. Proliferative cells in vivo were labeled by BrdU (bromodeoxyuridine, S phase cell cycle marker) combined to immunohistochemistry for the identification of BrdU antigen and the phosphorylated form of H3 ?histone (expressed at the end of G2 and during M phase of the cell cycle). We identified proliferative cells in mice MZ from embryonic day (E)14 (just after preplate division when MZ becomes distinguishable) and through all corticogenesis with a three fold increase in E18. Proliferative cells in the MZ do not express Pax6 or Tbr2, transcriptional factors typical of VZ and SVZ precursors respectively. During corticogenesis, this precursor population displays a latero-medial gradient of expression of Olig2, such that perinatally, all proliferative cells in the MZ express Olig2. Clonal lineage analysis from these precursors revealed a high gliogenic potential (~70% pure glial clones) when compared to VZ/SVZ (2,3%). Furthermore, MZ displays neurogenic potential since 30% of all clones contained neurons identified by class III ?-tubulin immunolabeling. Here we show that pure glial clones in the MZ are significantly larger than those generated by VZ. Concluding, the dorsal MZ is a neurogenic and gliogenic niche in the developing cerebral cortex containing proliferative cells with distinct phenotypic characteristics from the VZ and SVZ. By clonal lineage analysis in vitro, we demonstrated different proliferative behaviors and neuro-gliogenic potential from cells isolated from the MZ and VZ/SVZ indicating a novel type of progenitor in the cerebral cortex.

Marginal zone (MZ) lymphomas (MZLs) represent a group of lymphomas originating from B lymphocytes of the “marginal zone” which is the external part of the secondary lymphoid follicles. The WHO classifies MZL into 3 entities; extranodal MZL, splenic MZL and nodal MZL. Extranodal marginal zone lymphoma (EMZL) can arise in different tissues, including the stomach, salivary gland, lung, small bowel, thyroid, ocular adnexa and skin. We present a 25 years old female with a history of angioedema and chronic cutaneous eczema who developed an unusual EMZL. Patient presented with a history of rapidly enlarging skin nodule on her left elbow that had been present for almost one year. Over a period of 2-3 weeks she felt the nodule rapidly changed in size and shape. Excisional biopsy of the mass revealed a lymphoid infiltrate based in the reticular dermis and focally extending into the subcutaneous adipose tissue with formation of disrupted lymphoid follicles positive for CD20, CD23 and BCL2 but negative for CD10, Cyclin D1 and SOX11. Diagnosis was consistent with extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). Patient on presentation did not have any B symptoms other cutaneous lesions, lymphadenopathy or hepatosplenomegaly. PET scan revealed no evidence of abnormal uptake leading to a final Stage IE definition. Patient initiated definitive radiation therapy. EMZL accounts for 5 -10 % of non-Hodgkin lymphoma. It has been described often in organs that are normally devoid of germinal centers. It may arise in reactive lymphoid tissue induced by chronic inflammation in extranodal sites. Primary cutaneous marginal zone lymphoma (PCMZL) is associated with infectious etiologies such as Borrelia burgdorferi and less commonly with viral infections or in relation to autoimmune disorders. Autoimmune disorders, specifically Sjögren's syndrome is associated with a 30-fold increased risk of marginal zone lymphoma. Localized disease can be treated by local radiotherapy, intralesional injections or excision. Widespread skin disease is usually treated with a CD20 directed monoclonal antibody-Rituximab. Patients with PCMZL usually have an indolent clinical course. Extracutaneous dissemination of MALT Lymphoma is uncommon and happens in 6-8 % of patients. The 5 years overall survival is between 98-100%. Family physicians and dermatologists should have a high index of suspicion for this rare lymphoma subtype especially in patients with inflammatory chronic skin conditions and atopy.