Immunoglobulin gene rearrangements and the pathogenesis of multiple myeloma.

The ability to rearrange the germ-line DNA to generate antibody diversity is an essential prerequisite for the production of a functional repertoire. While this is essential to prevent infections, it also represents the "Achilles heel" of the B-cell lineage, occasionally leading to malignant transformation of these cells by translocation of protooncogenes into the immunoglobulin (Ig) loci. However, in evolutionary terms this is a small price to pay for a functional immune system. The study of the configuration and rearrangements of the Ig gene loci has contributed extensively to our understanding of the natural history of development of myeloma. In addition to this, the analysis of Ig gene rearrangements in B-cell neoplasms provides information about the clonal origin of the disease, prognosis, as well as providing a clinical useful tool for clonality detection and minimal residual disease monitoring. Herein, we review the data currently available on both Ig gene rearrangements and protein patterns seen in myeloma with the aim of illustrating how this knowledge has contributed to our understanding of the pathobiology of myeloma.

Improved clonality assessment in germinal centre/post-germinal centre non-Hodgkin's lymphomas with high rates of somatic hypermutation.

BACKGROUND: PCR detects clonal rearrangements of the Ig gene in lymphoproliferative disorders. False negativity occurs in germinal centre/post-germinal centre lymphomas (GC/PGCLs) as they display a high rate of somatic hypermutation (SHM), which causes primer mismatching when detecting Ig rearrangements by PCR. AIMS: To investigate the degree of SHM in a group of GC/PGCLs and assess the rate of false negativity when using BIOMED-2 PCR when compared with previously published strategies. METHODS: DNA was isolated from snap-frozen tissue from 49 patients with GC/PGCL (23 diffuse large B cell lymphomas (DLBCLs), 26 follicular lymphomas (FLs)) and PCR-amplified for complete (VDJH), incomplete (DJH) and Ig kappa/lambda rearrangements using the BIOMED-2 protocols, and compared with previously published methods using consensus primers. Germinal centre phenotype was defined by immunohistochemistry based on CD10, Bcl-6 and MUM-1. RESULTS: Clonality detection by amplifying Ig rearrangements using BIOMED-2 family-specific primers was considerably higher than that found using consensus primers (74% DLBCL and 96% FL vs 69% DLBCL and 73% FL). Addition of BIOMED-2 DJH rearrangements increased detection of clonality by 22% in DLBCL. SHM was present in VDJH rearrangements from all patients with DLBCL (median (range) 5.7% (2.5-13.5)) and FL (median (range) 5.3% (2.3-11.9)) with a clonal rearrangement. CONCLUSIONS: Use of BIOMED-2 primers has significantly reduced the false negative rate associated with GC/PGCL when compared with consensus primers, and the inclusion of DJH rearrangements represents a potential complementary target for clonality assessment, as SHM is thought not to occur in these types of rearrangements.

Molecular characteristics and gene segment usage in IGH gene rearrangements in multiple myeloma.

BACKGROUND AND OBJECTIVES: Analysis of IgH rearrangements in B-cell malignancies has provided clinical researchers with a wide range of information during the last few years. However, only a few studies have contributed to the characterization of these features in multiple myeloma (MM), and they have been focused on the analysis of the expressed IgH allele only. Comparison between the expressed and the non-functional IgH alleles allows further characterizion of the selection processes to which pre-myeloma cells are submitted. DESIGN AND METHODS: We analyzed a cohort of 84 untreated MM patients in order to characterize their functional VDJH and non-functional DJH rearrangements. The pattern of mutations and gene segment usage for both types of rearrangements was analyzed by polymerase chain reaction and sequencing. RESULTS: VH3 and VH1 family members were over- and under-represented, respectively. VH3-30 and VH3-15 segments were the most frequently used, whereas VH4-34 was found only in non-functional or heavily mutated VDJH rearrangements. DH2 and DH3 family members were over-represented in both VDJH and DJH repertoires, while the DH1 family was under-represented only in the productive VDJH rearrangements. Finally, DH3-22 and DH2-21 gene segments were found to be over-represented in the functional repertoire while segments commonly used by less mature B-cell malignancies, such as DH6-19 or DH3-3, were under-represented. INTERPRETATION AND CONCLUSIONS: Data reported here help to identify the clonogenic MM cell as a post-germinal center B cell that has undergone selection processes during the germinal center reaction.

Incomplete DJH rearrangements.

Analysis of Ig genes in B-cell malignancies has become an essential method in molecular diagnosis, and polymerase chain reaction (PCR) amplification of Ig heavy chain gene (IgH) rearrangements is now widely used for detection of clonality and minimal residual disease (MRD). Although several different sensitive protocols are now available for PCR analysis of IgH genes, they are frequently hampered owing to the high rate of somatic hypermutation present in multiple myeloma (MM). We recently described a new approach using incomplete DJH rearrangements as an alternative target. About 60% of MM samples contain an incomplete DJH rearrangement, 90% of them lacking on somatic mutations. This approach allows resolution of problems derived from primer mismatches, making DJH rearrangement a reliable and sensitive target for detection of clonality and MRD investigation in MM.

Insights into the multistep transformation of MGUS to myeloma using microarray expression analysis.

To define specific pathways important in the multistep transformation process of normal plasma cells (PCs) to monoclonal gammopathy of uncertain significance (MGUS) and multiple myeloma (MM), we have applied microarray analysis to PCs from 5 healthy donors (N), 7 patients with MGUS, and 24 patients with newly diagnosed MM. Unsupervised hierarchical clustering using 125 genes with a large variation across all samples defined 2 groups: N and MGUS/MM. Supervised analysis identified 263 genes differentially expressed between N and MGUS and 380 genes differentially expressed between N and MM, 197 of which were also differentially regulated between N and MGUS. Only 74 genes were differentially expressed between MGUS and MM samples, indicating that the differences between MGUS and MM are smaller than those between N and MM or N and MGUS. Differentially expressed genes included oncogenes/tumor-suppressor genes (LAF4, RB1, and disabled homolog 2), cell-signaling genes (RAS family members, B-cell signaling and NF-kappaB genes), DNA-binding and transcription-factor genes (XBP1, zinc finger proteins, forkhead box, and ring finger proteins), and developmental genes (WNT and SHH pathways). Understanding the molecular pathogenesis of MM by gene expression profiling has demonstrated sequential genetic changes from N to malignant PCs and highlighted important pathways involved in the transformation of MGUS to MM.

Incomplete DJH rearrangements of the IgH gene are frequent in multiple myeloma patients: immunobiological characteristics and clinical implications.

DH-JH rearrangements of the Ig heavy-chain gene (IGH) occur early during B-cell development. Consequently, they are detected in precursor-B-cell acute lymphoblastic leukemias both at diagnosis and relapse. Incomplete DJH rearrangements have also been occasionally reported in mature B-cell lymphoproliferative disorders, but their frequency and immunobiological characteristics have not been studied in detail. We have investigated the frequency and characteristics of incomplete DJH as well as complete VDJH rearrangements in a series of 84 untreated multiple myeloma (MM) patients. The overall detection rate of clonality by amplifying VDJH and DJH rearrangements using family-specific primers was 94%. Interestingly, we found a high frequency (60%) of DJH rearrangements in this group. As expected from an immunological point of view, the vast majority of DJH rearrangements (88%) were unmutated. To the best of our knowledge, this is the first systematic study describing the incidence of incomplete DJH rearrangements in a series of unselected MM patients. These results strongly support the use of DJH rearrangements as PCR targets for clonality studies and, particularly, for quantification of minimal residual disease by real-time quantitative PCR using consensus JH probes in MM patients. The finding of hypermutation in a small proportion of incomplete DJH rearrangements (six out of 50) suggests important biological implications concerning the process of somatic hypermutation. Moreover, our data offer a new insight in the regulatory development model of IGH rearrangements.

Low frequency of the TEL/AML1 fusion gene in acute lymphoblastic leukaemia in Spain.

We report on a series of Spanish patients with acute lymphoblastic leukaemia in whom the t(12;21) [TEL/AML1] translocation could not be identified with two sensitive techniques: reverse transcript-polymerase chain reaction (RT-PCR) and fluorescence in-situ hybridization (FISH). 101 cases were analysed: 38 children (29 B-cell precursor; nine T-cell precursor) and 63 adults (48 B-cell precursor; 15 T-cell precursor). Specific RT-PCR to amplify the TEL/AML1 fusion transcript was negative in all 101 cases. Moreover, all 38 paediatric samples were also negative by interphase FISH analysis for the presence of the TEL/AML1 fusion. These results suggest the existence of geographic/race variations in the genotype of acute lymphoblastic leukaemia (ALL).

Heteroduplex PCR analysis of rearranged immunoglobulin genes for clonality assessment in multiple myeloma.

BACKGROUND AND OBJECTIVE: Molecular analysis by PCR of monoclonally rearranged immunoglobulin (Ig) genes can be used for diagnosis in B-cell lymphoproliferative disorders (LPD), as well as for monitoring minimal residual disease (MRD) after treatment. This technique has the risk of false-positive results due to the "background" amplification of similar rearrangements derived from polyclonal B-cells. This problem can be resolved in advance by additional analyses that discern between polyclonal and monoclonal PCR products, such as the heteroduplex analysis. A second problem is that PCR frequently fails to amplify the junction regions, mainly due to somatic mutations frequently present in mature (post-follicular) B-cell lymphoproliferations. The use of additional targets (e.g. Ig light chain genes) can avoid this problem. DESIGN AND METHODS: We studied the specificity of heteroduplex PCR analysis of several Ig junction regions to detect monoclonal products in samples from 84 MM patients and 24 patients with B cell polyclonal disorders. RESULTS: Using two distinct VH consensus primers (FR3 and FR2) in combination with one JH primer, 79% of the MM displayed monoclonal products. The percentage of positive cases was increased by amplification of the Vlamda-Jlamda junction regions or kappa(de) rearrangements, using two or five pairs of consensus primers, respectively. After including these targets in the heteroduplex PCR analysis, 93% of MM cases displayed monoclonal products. None of the polyclonal samples analyzed resulted in monoclonal products. Dilution experiments showed that monoclonal rearrangements could be detected with a sensitivity of at least 10(-2) in a background with >30% polyclonal B-cells, the sensitivity increasing up to 10(-3) when the polyclonal background was

TRIB2 in normal and malignant hematopoiesis - a transcription factor network

Hematopoiesis is the tightly controlled and complex process in which the entire blood system is formed and maintained by a rare pool of hematopoietic stem cells (HSCs), and its dysregulation results in the formation of leukaemia. TRIB2, a member of the Tribbles family of serine/threonine pseudokinases, has been implicated in a variety of cancers and is a potent murine oncogene that induces acute myeloid leukaemia (AML) in vivo via modulation of the essential myeloid transcription factor CCAAT-enhancer binding protein α (C/EBPα). C/EBPα, which is crucial for myeloid cell differentiation, is commonly dysregulated in a variety of cancers, including AML. Two isoforms of C/EBPα exist - the full-length p42 isoform, and the truncated oncogenic p30 isoform. TRIB2 has been shown to selectively degrade the p42 isoform of C/EBPα and induce p30 expression in AML. In this study, overexpression of the p30 isoform in a bone marrow transplant (BMT) leads to perturbation of myelopoiesis, and in the presence of physiological levels of p42, this oncogene exhibited weak transformative ability. It was also shown by BMT that despite their degradative relationship, expression of C/EBPα was essential for TRIB2 mediated leukaemia. A conditional mouse model was used to demonstrate that oncogenic p30 cooperates with TRIB2 to reduce disease latency, only in the presence of p42. At the molecular level, a ubiquitination assay was used to show that TRIB2 degrades p42 by K48-mediated proteasomal ubiquitination and was unable to ubiquitinate p30. Mutation of a critical lysine residue in the C-terminus of C/EBPα abrogated TRIB2 mediated C/EBPα ubiquitination suggesting that this site, which is frequently mutated in AML, is the site at which TRIB2 mediates its degradative effects. The TRIB2-C/EBPα axis was effectively targeted by proteasome inhibition. AML is a very difficult disease to target therapeutically due to the extensive array of chromosomal translocations and genetic aberrations that contribute to the disease. The cell from which a specific leukaemia arises, or leukaemia initiating cell (LIC), can affect the phenotype and chemotherapeutic response of the resultant disease. The LIC has been elucidated for some common oncogenes but it is unknown for TRIB2. The data presented in this thesis investigate the ability of the oncogene TRIB2 to transform hematopoietic stem and progenitor cells in vitro and in vivo. TRIB2 overexpression conferred in vitro serially replating ability to all stem and progenitor cells studied. Upon transplantation, only TRIB2 overexpressing HSCs and granulocyte/macrophage progenitors (GMPs) resulted in the generation of leukaemia in vivo. TRIB2 induced a mature myeloid leukaemia from the GMP, and a mixed lineage leukaemia from the HSC. As such the role of TRIB2 in steady state hematopoiesis was also explored using a Trib2-/- mouse and it was determined that loss of Trib2 had no effect on lineage distribution in the hematopoietic compartment under steady-state conditions. The process of hematopoiesis is controlled by a host of lineage restricted transcription factors. Recently members of the Nuclear Factor 1 family of transcription factors (NFIA, NFIB, NFIC and NFIX) have been implicated in hematopoiesis. Little is known about the role of NFIX in lineage determination. Here we describe a novel role for NFIX in lineage fate determination. In human and murine datasets the expression of Nfix was shown to decrease as cells differentiated along the lymphoid pathway. NFIX overexpression resulted in enhanced myelopoiesis in vivo and in vitro and a block in B cell development at the pre-pro-B cell stage. Loss of NFIX resulted in disruption of myeloid and lymphoid differentiation in vivo. These effects on stem and progenitor cell fate correlated with changes in the expression levels of key transcription factors involved in hematopoietic differentiation including a 15-fold increase in Cebpa expression in Nfix overexpressing cells. The data presented support a role for NFIX as an important transcription factor influencing hematopoietic lineage specification. The identification of NFIX as a novel transcription factor influencing lineage determination will lead to further study of its role in hematopoiesis, and contribute to a better understanding of the process of differentiation. Elucidating the relationship between TRIB2 and C/EBPα not only impacts on our understanding of the pathophysiology of AML but is also relevant in other cancer types including lung and liver cancer. Thus in summary, the data presented in this thesis provide important insights into key areas which will facilitate the development of future therapeutic approaches in cancer treatment.

Immunogenicity of Outer Membrane Proteins VirB9-1 and VirB9-2, a Novel Nanovaccine against Anaplasma marginale

Anaplasma marginale is the most prevalent tick-borne livestock pathogen and poses a significant threat to cattle industry. In contrast to currently available live blood-derived vaccines against A. marginale, alternative safer and better-defined subunit vaccines will be of great significance. Two proteins (VirB9-1 and VirB9-2) from the Type IV secretion system of A. marginale have been shown to induce humoral and cellular immunity. In this study, Escherichia coli were used to express VirB9-1 and VirB9-2 proteins. Silica vesicles having a thin wall of 6 nm and pore size of 5.8 nm were used as the carrier and adjuvant to deliver these two antigens both as individual or mixed nano-formulations. High loading capacity was achieved for both proteins, and the mouse immunisation trial with individual as well as mixed nano-formulations showed high levels of antibody titres over 107 and strong T-cell responses. The mixed nano-formulation also stimulated high-level recall responses in bovine T-cell proliferation assays. These results open a promising path towards the development of efficient A. marginale vaccines and provide better understanding on the role of silica vesicles to deliver multivalent vaccines as mixed nano-formulations able to activate both B-cell and T-cell immunity, for improved animal health.

Studies on the protective immune response to Plasmodium chabaudi in mice

Inbred strains of C5731 and NIH nice infected with the A/S strain of Plasmodium chaubaudi usually developed high parasitaemias but infections were rarely fatal in immunocompetent mice and in most mice the parasites could be eradicated within 53 days or less. The immune response of C57B1 and NTH mice to infection with the A/S strain of P. chabaudi was studied. The principle method used in this study for investigating the immune response of the mice was to examine the immunity conferred on syngeneic mice, either X-irradiated or non-irradiated, by transferring to them lymphoid cells or serum from immune or semi-immune donors. The lymphoid cell populations examined were unfractionated spleen cells, nylon wool column enriched subpopulations of thymus-derived lymphocytes (T cells) and the so-called bursa-derived lymphocytes (B cells), bone marrow cells and phagocytic cells. In the course of these experiments observations were made on the effect of X-irradiation on the subsequent growth and multiplication of the parasite. In addition, an in vitro assay for antibody-dependent cell mediated cytotoxicity was used to investigate the activity of splenic K cells during malaria infection. K cells are lymphoid cells which may include lymphocytes of an undefined category, but possess receptors for the Fc portion of antibody on their surface and have the ability to non-specifically lyse target cells coated in antibodies. a) The adoptive transfer of immunity to P.chabaudi with immune spleen cells. Spleen cells from mice which had previously been infected with P.chabaudi were able to confer some immunity on syngeneic mice which had been irradiated with 600 or 800 rads. The protection was detected as a shortened patent parasitaemia in immune cell recipients compared to controls. The early experiments indicated the value of using irradiated recipients rather than non-irradiated recipients. In irradiated mice, a) smaller numbers of immune cells were required to promote detectable immunity than in non-irradiated mice, b) there was an amplification of the difference in the duration of primary parasitaemias in recipients of immune cells and normal cells compared to non-irradiated mice and c) as the irradiated host is immunodepressed, the protective effect of donor cells can be examined with a reduced contribution by the hosts own immune system. An initial non-specific resistance to P.chabaudi infection was observed in irradiated mice, although the infection in most of these mice was subsequently more severe than in non-irradiated mice. The non-specific resistance could be reduced or abolished by injecting lymphoid cells into mice shortly after irradiation or by infecting irradiated mice more than 15 days after irradiation. Other workers suggest that following irradiation, the reticulo-endothelial system is stimulated at the time that the non-specific resistance to P.chabaudi was observed. b) the adoptive transfer of immunity in syngeneic mice with enriched subpopulations of splenic immune T cells, B. cells, bone marrow cells and phagocytes. Immunity to P.chabaudi could be adoptively transferred with enriched spleen subpopulations of immune T cells or immune B cells in mice which had been irradiated 600 or 300 rads. The protective effects of unfractionated immune cells was, however, usually better than that of either immune T or F cell subpopulations. In most experiments enriched immune T cell recipients were more likely to suffer relapsing patent parasitaemias than either enriched immune B cell recipients or unfractionated immune cell recipients. In one experiment a comparison was made of the course of P.chabaudi infection in mice which had been irradiated with either 600 rads or 300 rads and which received injections of different immune cells. A dose of 600 rads permits the immune system of mice to recover from the effects of irradiation, but a dose of 800 rads is lethal to mice unless lymphoid cells are injected after irradiation. It was found that in recipients of enriched immune T or B cells, which had been irradiated with 600 rads, the parasitaemia became subpatent before their equivalents irradiated with 800 rads, but that there was little difference in parasitaemias between recipients of unfractionated immune cells given 600 or 800 rads. Experiments in which enriched immune T cells and B cells were recombined and injected into syngeneic mice gave inconclusive results as to whether the immune subpopulations acted synergistically. Similar experiments in which immune subpopulations of lymphoid cells were recombined with normal subpopulations of lymphoid cells demonstrated that the latter cells did not enhance the protective effect of the former cells. Bone marrow cells from immune mice were able to confer some protection on syngeneic recipients, but were not as protective as enriched immune T cells or B cells. The results obtained in adoptive transfer experiments using phagocytic cells from the spleen of immune mice depended on the length of time spleen cells were incubated in petri-dishes at 37° C before harvesting the phagocytes. Using C57B1 mice, phagocytes harvested after 15 hours incubation were as protective as unfractionated immune cells in a cell transfer experiment, but phagocytes harvested after 16 hours incubation were not protective. Examination of NIH phagocytic cells after 2.5 hours incubation at 37°C, which were as protective as unfractionated immune spleen cells in a cell transfer experiment, demonstrated that the petri-dish adherent cells may have contained B lymphocytes. c) The passive transfer of immunity with serum from P.chabaudi infected mice. The passive transfer of serum from C57B1 mice which had been previously infected with P.chabaudi to normal or irradiated syngeneic mice demonstrated that the serum recipients were initially protected from infection. Irradiated mice, however, were delayed longer in the onset of parasitaemia compared to non-irradiated mice. Using NIH mice, sera were collected from unfractionated immune spleen cell recipients, enriched immune T cell recipients and normal spleen recipients on the 11th day of a P.chabaudi infection, just after peak parasitaemia, and also on the 14th day of infection. On day 14, all immune cells recipients and most of the enriched immune T cell recipients had become subpatent but all normal cell recipients still had patent infections. Sera collected from the different spleen cell recipients on the 11th day of infection and passively transferred to irradiated mice demonstrated little protection. Sera collected on the 14th day of infect ion, however, reflected the immune status of the donors in their protective properties in mice infected with P.chabaudi. The serum from unfractionated immune cell recipients was the most protective of the 3 sera when compared to normal NIH serum and the serum from enriched immune T cell recipients was slightly protective, but the serum from normal cell recipients produced an enhanced infection in mice infected with P.chabaudi. d) Antibody-dependent cell-mediated cytotoxicity of spleen cells in P.chabaudi infected mice. In a preliminary investigation of K cell activity in the spleens of P.chabaudi infected mice, it was found that there was an increased activity of K cells collected at around peak parasitaemia compared to the activity of K cells in non-infected mice, and that this increased activity could also be found in mice which had recently become subpatent. As the target cell for antibody-dependent cell-mediated cytotoxicity employed was the thick red blood cell, it is not known whether the K cell is involved in the killing of P.chabaudi parasites. These results suggest that both T cells and B cells and antibody may be important in the immune response to P.chabaudi in mice. Primed T cells may act as helper cells in the production of malarial antibodies, but, as enriched primed T cells could confer protection on immunodepressed mice, it is possible that a cell-mediated mechanism of immunity may also exist.

Intravascular Lymphoma as an Uncommon Cause of Anasarca

Objectives: To report a case of intravascular lymphoma (IVL) in a Caucasian patient who presented with anasarca as his sole clinical sign. Material and Methods: A man presented with anasarca-type oedema and fatigue. After excluding heart failure, hepatic cirrhosis, nephrotic syndrome, hypothyroidism, AL-amyloidosis and adverse drug reaction which can all cause oedema, we turned our attention to capillary permeability disorders. Results: Closer review of the bone marrow aspirate demonstrated haemophagocytic histiocytosis, while core, renal and duodenal biopsies showed a B-cell IVL. Conclusion: The differential diagnosis of anasarca, a relatively common clinical sign, should include IVL although the diagnosis may still be challenging.

Investigating mushroom LMW compounds as potential Bcl-2 inhibitors: docking studies using AutoDock4

The B cell CLL/lymphoma-2 (Bcl-2) family is functionally classified as either anti-apoptotic or pro-apoptotic, and the regulation of its interactions dictates survival or commitment to apoptosis. Bcl-2 family is also implicated in a wide range of diseases. In some types of cancers, including lymphomas and epithelial cancers, protein overexpression of anti-apoptotic Bcl-2 family, such as the Bcl-2 protein is indicative of cancer in an advanced stage, with a poor prognosis and resistant to chemotherapy [1]. Several reports indicate that mushrooms have the ability to promote apoptosis in tumour cell lines, but the mechanism of action is not fully understood. Inhibition of the interaction between Bcl-2 (anti-apoptotic protein) and proapoptotic proteins could be an important step in the mechanism of mushroom induced apoptosis. Therefore, the discovery of compounds with the capacity to inhibit Bcl-2 is an ongoing research topic on cancer therapy. In this work, docking studies were performed using a dataset of 40 low molecular weight (LMW) compounds present in mushrooms. The docking software AutoDock 4 was used and docking studies were performed using 5 selected Bcl-2 crystal structures as targets. Compounds with the lowest predicted binding energy (predΔG) are expected to be the more potent inhibitors. Among the tested compounds, steroids presented the lowest predΔG with several exhibiting values below -9 kcal/mol. The results are corroborated by several reports that state that steroids induce apoptosis in several tumor cells. It is thus feasible that they might act by preventing Bcl-2 from forming complexes with the respective proapoptotic protein interaction partners, namely Bak, Bax, and Bim. Moreover, previous studies on our research group demonstrated that 48 h treatment of MCF-7 cells (breast carcinoma) with Suillus collinitus methanolic extract caused a decrease in Bcl-2, highlighting the antitumor potential of this mushroom species [2]. In conclusion, the process of apoptosis promoted by mushroom extracts may be related to the inhibition of Bcl-2 by the steroid derivatives herein studied. However, further studies are needed to confirm this hypothesis.

Linfoma primário da vagina – revisão da literatura a propósito de um caso clínico

Os tumores primários malignos da vagina são raros, contribuindo apenas para cerca de 1%-2% dos cancros ginecológicos. O linfoma não-Hodgkin (LNH) primário da vagina é raríssimo (existindo aproximadamente 100 casos descritos na literatura). A sua associação com infecção pelo vírus Epstein Barr (VEB) foi descrita em escassos casos. Os autores pretendem fazer uma revisão da literatura de linfoma primário da vagina, com base num caso clínico de LNH-B de grandes células numa mulher nulípara de 25 anos de idade.

Early growth response genes 2 and 3 regulate the expression of Bcl6 and differentiation of T follicular helper cells

T follicular helper (Tfh) cells support differentiation of B cells to plasma cells and high affinity antibody production in germinal centers (GC) and Tfh differentiation requires the function of B cell lymphoma 6 (Bcl6). We have now discovered that early growth response gene (Egr) 2 and 3 directly regulate the expression of Bcl6 in Tfh cells which is required for their function in regulation of GC formation. In the absence of Egr2 and 3, the expression of Bcl6 in Tfh cells is defective leading to impaired differentiation of Tfh cells resulting in a failure to form GCs following virus infection and defects in production of anti-viral antibodies. Enforced expression of Bcl6 in Egr2/3 deficient CD4 T cells partially restored Tfh differentiation and GC formation in response to virus infection. Our findings demonstrate a novel function of Egr2/3 which is important for Tfh cell development and Tfh cell mediated B cell immune responses.