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The expression of apoptosis-regulating proteins, Bcl-2, Bax, Mcl-1, and Bcl-X, was evaluated by immunohistochemical methods in 39 cases of thyroid carcinomas. Normal thyroid tissues showed a consistent expression of Bcl-2 and Mcl-1 whereas Bax and Bcl-X proteins were essentially absent from most follicular thyroid cells. Bax expression was observed in all papillary carcinomas (n = 23) and in 8 of 10 follicular carcinomas. The intensity of Bcl-2 immunostaining was generally higher in follicular tumors (n = 10) than in papillary carcinomas (n = 21 of 23). However, in undifferentiated tumors, both Bax and Bcl-2 were weakly expressed. Mcl-1 protein expression was similar to that of Bax in papillary and follicular tumors, but was also frequently detectable in undifferentiated tumors. Bcl-X immunostaining was seen in all undifferentiated tumors (n = 6), in 22 of 23 papillary tumors, and in 5 of 10 follicular tumors. Our findings show that the regulation of bcl-2 family gene expression is different in normal thyroid tissue compared to that of its neoplastic counterpart and varies with the tumor subtype. In particular, unlike normal thyroid epithelium, the apoptosis-blocking gene bcl-X and the apoptosis-inducing gene bax are frequently expressed in thyroid carcinomas derived from the follicular cells. Thus, alterations in the expression of these bcl-2 family genes may contribute to the pathogenesis of thyroid carcinomas.

We describe an "inflammatory pseudotumor" of the liver that, which on detailed investigation, proved that the spindle-cell component of this lesion is derived from follicular dendritic reticulum cells (FDRC). This contention is supported by morphologic observations and by immunophenotype. The FDRC population contain Epstein-Barr virus (EBV). It is known that FDRC express the EBV receptor CD21. In this particular case, the FDRC contained clonal EBV genomes, EBV RNA (EBER) transcripts, and expressed EBV latent membrane protein (LMP1). DNA sequencing of PCR products showed three point mutations compared with the standard LMP1 sequence of the EBV strain B95-8. The findings in this case corroborate those of other investigators concerning the possible role of EBV in the development of some inflammatory pseudotumors, including the recent production of functionally active EBV-transformed FDRC-like cell lines. This association could prove instructive in delineating the histogenesis of these tumors and further assist in making prognostic and therapeutic decisions.

AIMS: (1) To assess the clonality of tumour cells in two patients with mycosis fungoides who subsequently developed Hodgkin9s disease; and (2) to determine whether there is a clonal relation between these two disorders. METHODS: Cutaneous tissue samples involved by mycosis fungoides and lymph nodes involved by Hodgkin9s disease from both patients were investigated by immunohistochemistry and the polymerase chain reaction. RESULTS: Mycosis fungoides tumour cells in both patients expressed multiple T cell associated antigens; Reed-Sternberg (RS) cells had the null phenotype. T cell receptor gamma chain genes were clonally rearranged in mycosis fungoides cells but not in RS cells, including variants, in both patients. In the patient with intermediate transformation to large cell lymphoma, immunoglobulin heavy chain genes were rearranged in the cutaneous tumour, but not in the lymph node involved by Hodgkin9s disease. CONCLUSION: The divergent antigen expression and gene rearrangements observed in these two patients strongly suggest that Hodgkin9s disease and mycosis fungoides are not derived from a single tumour cell clone.

The authors investigated 25 benign lymph nodes in patients infected with the human immunodeficiency virus (HIV) by in situ hybridization (ISH) and immunohistochemistry (IHC) to detect and characterize the Epstein-Barr virus (EBV)-infected cells. After ISH, 22 lymph nodes were found to contain various numbers of Epstein-Barr-encoded RNA (EBER)-positive cells. Most of these cells were B cells. In six lymph nodes with numerous EBV-infected cells, EBNA2-positive/LMP1-positive lymphoblastoid cells were detected by IHC. Exceptional cells (in two specimens) were positively labeled with antigen-Z Epstein-Barr replicative activator (ZEBRA) antibody or BamHI Left Frame 1/Not I (BHLF1/Not I) probes, indicating that EBV replication is not enhanced in the lymphocytes. In normal conditions (healthy individuals), small lymphocytes that express a restricted pattern of viral genes do escape immune response, whereas lymphoblastoid cells do not. Thus, impaired immune system may account for the late proliferation of lymphoblastoid cells (Epstein-Barr nuclear antigen [EBNA]2positive/latent membrane protein [LMP]1 positive) in HIV-infected patients, and could explain why EBV-driven, acquired immunodeficiency syndrome (AIDS)-related, non-Hodgkin's lymphoma occur more frequently in patients with low CD4-positive T cells.

This sequencing study of 17 acquired immunodeficiency syndrome-related lymphomas (9 primary brain, 8 systemic) and 8 human immunodeficiency virus-negative atypical lymphoproliferations expressing large amounts of the latent membrane protein 1 (LMP1) of Epstein-Barr virus was performed to characterize the carboxy terminal NF-kappa B activation domain of LMP1 at the molecular level in an immunocompromised host. In- frame deletions within the NF-kappa B activation domain were identified in all but 2 primary brain lymphomas, 4 systemic lymphomas, and 4 atypical lymphoproliferations, ie, in 60% of cases. In addition, non silent point mutations (range 1 to 5, mean 3.3) were detected in all cases. Although all changes occurred within the first 100 nucleotides of the carboxy terminal NF-kappa B activation domain--a critical sequence for the protein half-life--not a single point mutation was found in the remaining 62 nucleotides, necessary for malignant transformation. Such a clustering of nonrandom sequence variations, associated with a high oncoprotein expression in immunocompromised hosts, suggests that this part of the LMP1 oncogene behaves as a hypervariable region with natural selection of growth-promoting variants through prolongation of the protein half-life.

Bone marrow involvement by anaplastic large cell anaplastic large cell (ALC) lymphoma can be difficult to detect on routine morphologic examination alone. In a series of 42 patients with ALC lymphoma, the authors analyzed: (1) the usefulness of a limited panel of monoclonal antibodies directed against CD30 (Ber-H2, HRS4) and epithelial marrow involvement on routinely processed biopsy specimens; and (2) the prognostic significance of bone marrow involvement as detected on both morphologic and immunohistochemical grounds. On conventional examination, 17% of the patients were found to have bone marrow involvement at diagnosis. However, after immunohistochemical analysis, occult malignant cells were detected in 23% of the patients with negative bone marrow biopsy on routine histology. The low percentage of positive cases on routine morphologic examination compared to immunohistochemical examination was related to: (1) the scarcity of neoplastic cells which were scattered among hematopoietic cells; (2) the difficulty of distinguishing malignant cells from immature hematopoietic elements; and (3) the absence of alteration of the reticulin network. The authors observed a significant association between marrow infiltration and the presence of hematologic abnormalities (mostly anemia or cytopenias) at diagnosis, both in children and adult patients. More importantly, a significant lower survival was seen in patients with bone marrow involvement compared to those without bone marrow involvement. Immunohistochemistry with anti-CD30 and anti-EMA antibodies should be performed systematically in bone marrow biopsies from patients with ALC lymphoma to reliably identify the presence of bone marrow involvement that appears to carry a poor prognosis.

Summary Hodgkin's disease (HD) has been found to be linked to Epstein-Barr virus (EBV). Familial HD (FHD) may be related to a possible unknown agent. We have determined whether EBV small RNAs (EBERs) were found in Reed-Sternberg cells from FHD. Five families were studied for histological subtype and EBER presence. There was a striking similarity in FHD subtypes of each family and 3/11 (27%) of the cases were EBER positive. In conclusion, EBV EBERs are only infrequently found in FHD and other factors including viruses different from EBV should be further investigated in FHD.

OBJECTIVES--To determine whether the Epstein-Barr virus is present in synovial membranes and subcutaneous nodules of patients with rheumatoid arthritis. METHODS--A sensitive in situ hybridisation technique was applied to tissue sections of 11 synovial membranes and five rheumatoid nodules. RESULTS--Cells carrying the Epstein-Barr virus were not detected using EBER and BHLF1 oligonucleotides in the tissue samples investigated here. CONCLUSIONS--Although it has been suggested that the Epstein-Barr virus could play a part in the aetiology of rheumatoid arthritis, it was not detected in synovial membranes and subcutaneous lesions in this study.

Background/Aims —Primary central nervous system large B cell lymphomas (PCNSLs) are frequently associated with Epstein-Barr virus (EBV) in patients with AIDS and less frequently in those without AIDS. Human herpesvirus 8 (HHV-8) has been detected in these tumours by the polymerase chain reaction (PCR) at low copy number, suggesting its presence in a cell compartment other than the malignant one. The aim of this study was to use immunohistochemistry to assess HHV-8 infection in a series of PCNSLs from patients with and without AIDS. Methods —The antibody LN53, which reacts with the latent nuclear antigen 1 (LNA1) of HHV-8, was used on tissue sections from 35 patients (17 with and 18 without AIDS) with PCNSL. In addition, DNA was available for PCR (open reading frame 26 (ORF 26), ORF 72, ORF 75) in three patients (two without AIDS, one with AIDS). Results —None of the 35 cases contained either DNA sequences or LNA1 positive cells. Conclusions —These results confirm the lack of HHV-8 infection in tumour cells of PCNSL. In addition, HHV-8 infected bystander cells do not express LNA1 latent protein in this setting.

Abstract 5067 Background: Hematologic neoplasms associated with the chromosomal translocation t(2;11)(p21;q23) form a distinct genetic entity with diverse manifestations, and have been strongly linked with up-regulation of the microRNA miR-125b-1 (Bousquet et al, J Exp Med, 2008). Of 41 patients with myeloid malignancies and t(2;11)(p21;23) reported in the world's literature, all but 2 were cases of acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS), the latter cases frequently high-grade MDS transforming to AML. In 20 of 41 cases deletion of 5q was detected as a secondary cytogenetic abnormality. Only two cases of chronic myeloproliferative disorders associated with t(2;11)(p21;23) have been reported: one of chronic myeloid leukemia with a secondary t(9;22) (Ph) translocation (Royer-Pokora et al, Leukemia, 2003) and one of polycythemia vera (Acar et al, Amer J Hematol, 2006). We encountered a patient with a mixed myelodysplastic/myeloproliferative neoplasm clinically resembling polycythemia vera that was associated with t(2;11)(p21;q23) who was found to have persistent elevation in the blood of the microRNA miR-125b-1. Case Report: A 52 year-old male presented with upper extremity pain and headache. A CBC revealed the white blood cell count was 12.5 ×103/uL (55% neutrophils, 12% lymphocytes, 8% monocytes, 5% eosinophils, 21% basophils), red blood cell count 6.62 × 106/uL, hemoglobin 22.4 g/dL, hematocrit 68.1%, MCV 103 fL, and platelets 112 × 103/uL. Bone marrow aspiration and biopsy revealed a markedly hypercellular marrow (100%) with 1+ reticulin fibrosis, mild trilineal dysplastic morphology, and a blast count of 0.8%. Cytogenetic studies disclosed 46, XY, t(2;11)(p21;q23) [4]/46, idem, del (5)(q15q31) [4]/46, XY, del (5) (q13q31) [2]/46, XY[10]. FISH studies were negative for BCR/ABL1 fusion and MLL rearrangement. Molecular analysis for the JAK2V617F allele was negative. A diagnosis of mixed myelodysplastic/myeloproliferative neoplasm, unclassified was made (WHO 2008). The patient was begun on hydroxyurea, 500 mg daily. Four months after diagnosis the blood counts were within normal range, at which time quantitative real-time PCR (qRT-PCR; Bousquet et al, J Exp Med, 2008) performed on a sample of whole blood revealed a twenty-fold elevation of the microRNA species miR-125b-1, compared to healthy donors (n=3), and JAK2V617F-negative (n=3) and JAK2V617F-positive (n=2) polycythemia vera controls. Repeat qRT-PCR performed on whole blood 15 months after diagnosis confirmed persistently elevated miR-125b-1, nearly 200-fold above healthy donor controls (n=3). 18 months after diagnosis the patient remains healthy, with normal blood counts on 500 mg of hydroxyurea daily (white blood cell count 5.54 ×103/uL, red cell count 5.35 × 106/uL, hemoglobin 13.7 g/dL, hematocrit 47.2%, MCV 88.2, platelets 132.0 × 103/uL). Conclusion: This case expands the clinical-pathologic spectrum of hematologic malignancies associated with t(2;11)(p21;23), and confirms the link between t(2;11)(p21;23) and up-regulation of miR-125b-1. Translocation t(2;11)(p21;23) with miR-125b-1 up-regulation should be considered as a rare possibility in the differential diagnosis of JAK2V617F-negative polycythemia vera. Disclosures: No relevant conflicts of interest to declare.

3571 Background: Treatment of metastatic colorectal cancer with anti-EGFR is restricted to patients with wild-type KRAS tumor. The detection of KRAS mutation is easy to perform using several method...

Sixteen cases of primary anterior mediastinal B-cell lymphoma were characterized by morphologic, immunophenotypic, and clinical profiles. Twelve were men and four were women. The median age was 42 years. Virtually all tumors were of large cell type. Three main morphologic categories were identified, with one rare exception. In some tumors, the cells were compatible with centrocytes and centroblasts (four). Others had cells readily identifiable as centroblasts (six). Both these groups had a variable proportion of cells with multilobed nuclei. A third group was composed mainly of unclassifiable cells with multilobed nuclei (five). All had discernible sclerosis of varying intensity. A wider range of morphologic features and different sex distribution was noticed in comparison with previously reported clear cell features and younger women. The dominant phenotype of these B-cell lymphomas was CD19+, CD22+, CD37+, CD21-, CD30-, CD10-, CD5-, and Ig-negative. The finding of CD21-, Ig-negative phenotype, as observed by the authors and others, overlaps with some high-grade lymphomas of follicular center cell origin but is thought to bear similarity to a noncirculating population of thymic medullary B-cells. The tumors attained large size without peripheral dissemination and responded to chemotherapy as well as radiotherapy.

Most chromosomal translocations in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) involve oncogenes which are either up-regulated or form part of new chimeric genes. The t(2;11)(p21;q23) translocation has been cloned in 19 cases of MDS and AML. In addition to this, we have shown that this translocation is responsible for a strong up-regulation of miR-125b (6 to 90 fold). In vitro experiments revealed that miR-125b was able to block monocytic and granulocytic differentiation of leukemic cells and primary CD34+ human blasts. Therefore, miR-125b up-regulation may represent a new mechanism of myeloid cell transformation and myeloid neoplasms carrying the t(2;11) translocation define a new clinico-pathological entity.

Thirty cases of primary (23 cases) and secondary (seven cases) cutaneous B-cell lymphoma (CBCL) were studied by immunohistochemistry using a selected monoclonal antibody (MoAb) panel on both cryostat and paraffin sections. On cryostat sections all CBCL so tested were positive for surface membrane immunoglobulins (IgMk most often) and B-cell antigens (CD22+, CD37+) with a variable T-cell-reactive component identified by MoAbs against T-cell antigens (CD2, CD3, CD4, CD5, CD8). CD4-positive stromal T-cells were usually more numerous than CD8-positive cells. A strong (50-75% of total cells) stromal T-cell (CD2+, CD3+) reaction was found in centroblastic-centrocytic lymphoma. Small numbers of CD1+ Langerhans cells were found in most cases, but they were present in large numbers in follicular lymphoma. On paraffin sections, a combination of MoAbs against B-associated antigens (LN-1, MB2) identified B-cell lineage in virtually all cases of CBCL. CBCL was negative for MoAbs against T-associated antigens (MT1, UCHL1) with rare exceptions (two cases). However, MT1 and UCHL1 combined identified the T-cell nature of all cases of nonepidermotropic, nonmycosis T-cell lymphoma, which were initially predictive of B-lineage by histologic pattern.

Hemophagocytic syndrome (HPS) is characterized by an uncontrolled proliferation of macrophages displaying extensive phagocytosis of hematopoietic cells that can be associated with non Hodgkin lymphomas. However, Hodgkin lymphoma associated with hemophagocytic syndrome (HL-HPS) has rarely been published. We report here a large series of 34 patients presenting HL-HPS. Histological analysis and Epstein-Barr Virus (EBV) studies were performed. The 34 patients were enrolled from 1992 to 2006. HPS diagnosis was based on usual clinico-biological criteria. Bone marrow aspiration or biopsy were performed in all cases and confirmed HPS, showing hemophagocytic features in scattered macrophages. HL was documented on histological material in all 34 patients. The biopsies were performed on different localizations: lymph nodes (n=18), bone marrow (n=27), liver (n=2) and tonsil (n=1). All histological slides were reviewed and classified according to the World Health Organization (WHO) Lymphoma classification. The presence of EBV in the tumour cells was detected using EBER RNA in situ hybridization and the expression of viral proteins LMP-1, EBNA-2 by immunoperoxidase. Patients were 26 men and 8 women (sex ratio M/F = 3.3). The median age was 45 years (range 19–84). HIV status was negative in 26 patients and positive in 8 patients. All patients were in clinical stage IVB. HL subtypes (18 lymph nodes) were Mixed Cellularity (n=12, 67%), Nodular Sclerosis (n=2, 11%) and Lymphocyte Depleted (n=4, 22%). Extra nodal tissues were highly infiltrated by tumour cells in all cases. The presence of EBV in tumour cells was detected in 32 out of the 34 patients (94%). In all EBV positive cases, high levels of LMP-1 without EBNA2 expression were detected, defining a latency II. This study reports the largest series to date of HL-HPS. The features of HL-HPS are particular by the high proportion of mixed cellularity subtypes (67%) in contrast to the frequency of nodular sclerosis subtypes observed in the general population of non overt immunosuppressed patients, and by the striking high proportion of EBV associated HL (32 out of the 34 patients, 94%). Our findings suggest not only a pathogenic role of EBV, but also a defective immune system in the control of EBV infection in HL-HPS patients.The high predominance of male in our population of HPS-HL (sex ratio M/F = 4.3 after exclusion of HIV positive patients) and the strong association with EBV could suggest X-linked immune defect in these patients.

Allogeneic stem cell transplantation (SCT) can induce long-term disease-free survival in refractory follicular lymphomas (FL) but is impaired by high rate of transplant-related mortality (TRM). Reduced conditioning followed by allogeneic SCT is a promising concept in FL, allowing a graft-versus-lymphoma (GVL) effect while reducing the TRM. We piloted a clinical trial using this approach in relapsed/primary refractory low-grade lymphomas. From 1998 to 2003, 31 patients (pts) with an HLA-identical sibling have been enrolled. Main pts characteristics were : age = 49 years (range, 32–61 y); grade : I/II FL = 26; FL with histologic transformation = 5; gender = 16 male and 15 female; ≥ 2 prior therapies before transplantation = 23; primary refractory = 8; stage IV = 22; Bulky disease = 16; mean LDH rate before transplantation = 335 UI/l (range, 205–858); residual disease at transplantation (partial response (PR) + progression) = 20. Previous treatments were as follow : anthracyclins = 26, alkylants = 21, anti-CD20 = 15, purine analogs = 7, autologous SCT = 6, radiotherapy = 5. The conditioning regimen was IV fludarabine 30 mg/m²/day (from day −5 to −2); PO busulfan 2 mg/kg/day (from day −7 to −6); antithymocyte globulin (ATG) 2.5 mg/kg/day (from day −4 to −3). 14/31 (45%) and 17/31 (55%) pts received peripheral blood and bone marrow stem cells respectively with a median number of CD34+ cells of 5 x 106/kg (range, 1.8–11.9). Graft-versus-host-disease (GVHD) prophylaxis consisted in cyclosporine A alone. All patients achieved complete donor (> 95%) chimerism after allogeneic SCT. Median duration of neutropenia (< 0.5 G/L) and thrombocytopenia (< 25 G/L) were 3 days (range, 0–16) and 3 days (range, 0–29) respectively. 8/31 pts (26%) had CMV reactivation but no CMV disease. 3/31 (10%) developed grade II–IV acute GVHD. 10/31 (32%) developed chronic GVHD (5 moderate and 5 extensive). The median follow-up time was 20 months. The TRM was 19% (6/31). Causes of death were aGVHD = 1, auto-immune hepatitis = 1, bacteraemia = 2, pulmonary toxoplasmosis = 1 and Lyell syndrome = 1. Overall response rate was 97% (21 CR + 9 PR) at day 100 and at 1 year (24 CR + 6 PR). The estimated 2-year overall survival (OS), event-free survival (EFS) and relapse-free survival (RFS) rate were 75%, 65% and 85% respectively. 2 relapses occurred. Both were treated by anti-CD20, achieved CR and are still alive. Donor age, Bulky disease and LDH were significant for EFS. Altogether, these data suggest that non-myeloablative SCT can induce a high rate of durable remissions with reduced toxicity in this poor risk population.

Summary Drug hypersensitivity reactions can induce an atypical lymphoid infiltrate ranging from a benign condition to a malignant lymphoma. Here we describe two patients in whom atypical cutaneous lymphoid infiltrates developed while they were receiving losartan, an angiotensin II inhibitor.

A new B-lymphoma cell line (DEAU-cell line) was established from a diffuse large-cell lymphoma (centroblastic type) and was successfully grafted in athymic nude mice. Monoclonal antibodies (MoAbs) were generated using splenocytes of DEAU-tumor bearing mice. Before the fusion experiments, cellular immunity of the mice bearing growing DEAU tumors was restored by injection of spleen cells from conventional Balb/C mice. Spleen cells from conventional Balb/C mice immunized with DEAU-cell line were also used for the generation of MoAbs. Four MoAbs (DBB.42 and DBA.44 from normal Balb/C mice, and DNA.7 and DND.53 from athymic nude mice) were investigated because they identified B-cell- associated antigens not destroyed by fixatives. DBB.42 recognized a pan- B cell-associated antigen (molecular weight (mol wt) = 45 Kd). DBA.44 detected a B-cell antigen (mol wt not determined) expressed on a subpopulation of B lymphocytes in the mantle zone of lymphoid follicles. DNA.7 also defined a B-cell antigen (43 Kd) mainly expressed on germinal center cells. Similarly, DND.53 recognized a B-cell antigen (two bands of mol wt 20 Kd and 35 Kd, respectively) mainly expressed on germinal center cells and mantle zone lymphocytes and interdigitating reticulum cells in the paracortical area. Major differences were found in the reactivities of these MoAbs on malignant lymphomas. DBB.42 was positive with almost all B-cell lymphomas and some T-cell lymphomas. Within the group of low-grade B-cell lymphomas, DBA.44 reacted principally with hairy-cell leukemia. DNA.7 reacted mainly with high- grade B-cell lymphomas with a weak positivity in low-grade B-cell lymphomas. DND.53 reacted with all but one B-cell lymphoma, cells of histiocytosis X, and Reed-Sternberg cells. These findings indicate that new MoAbs can be generated by using spleen cells from athymic mice bearing human tumors as well as by new lymphoid cell lines. The MoAbs so generated, as in the present study, are deemed potentially useful for the recognition of B-cell lymphomas in routine diagnostic histopathology. In addition, DND.53 could be of value for the diagnosis of histiocytosis X and the detection of Reed-Sternberg cells in Hodgkin's disease.

The study examined the morphology and frequency of cell death occurring spontaneously in lymph nodes from patients with Hodgkin's disease. In addition to necrosis, which was infrequent and usually in patches, we document two cell types showing features of individual cell death: mummy cells end apoptotic cells. Mummy cells present no evidence of DNA fragmentation, but show electron microscopic features of "dark cells." Apoptotic Hodgkin-Reed-Sternberg cells are found frequently and are easier to demonstrate by in situ and labeling of fragmented DNA than by light microscopy only. In many cases phagocytosis of apoptotic cells is also documented. The significance of these findings to the limited number of Hodgkin-Reed-Sternberg cells in most cases of Hodgkin's disease is discussed.

PAX5 is a transcription factor central to B-cell differentiation, frequently mutated in pediatric B-ALL (38.9% in 192 B-ALL, Nature,2007;446:758). PAX5 mutations consist in whole or partial gene deletions or amplifications, fusion gene or point mutations. Adult B-ALL differs in many regards from pediatric B-ALL as demonstrated by differences in prognosis and genetic abnormalities (ETV6-RUNX1 almost absent from adult; BCR-ABL1 rare in children). We screened the occurrence of PAX5 mutations in a series of 119 adult patients with B-lineage ALL prospectively treated in the GRAALL-2003 (pediatric-like protocol for BCR-ABL1 negative patients) or GRAAPH-2003 (imatinib-containing protocol for BCR-ABL1 positive patients), with a median follow-up of 667 days. PAX5 copy number was evaluated using quantitative PCR of each exon performed in hexaplicate (10 exons). PAX5 point mutations of the paired and transactivation domains (exons 2, 3, 7, 8 and 9) were evaluated by sequence analysis. PAX5 rearrangement was evaluated by caryotype and FISH analysis. Globally, PAX5 mutations were identified in 35 cases (30%). Isolated complete deletion of 1 allele was found in 13 cases (11%). Hypomorphic PAX5 alleles were detected in 22 cases (19%) consisting either of partial deletion (13 cases), partial amplification (1), point mutations (7 cases, frequently associated with complete deletion of the remaining allele in 5 cases) or fusion gene (1 PAX5-ELN). In addition, 2 cases of whole PAX5 amplification were found (2%). The remaining 82 cases had two normal PAX5 alleles (68%). BCR-ABL1 fusion gene was significantly associated with PAX5 mutations (Pearson Chi2, p=0.045) occurring in 40% of patients with PAX5 mutations and 18.3% without. PAX5 mutations were rare in the early stages of B-ALL as estimated by the immunological EGIL classification (only 2/35 PAX5 mutant cases [5.7%] vs. 16/82 [19.5%] in normal PAX5 B-ALL cases blocked at the B-I stage). Frequencies of CD10+ and CD20+ blasts were significantly higher in PAX5 mutant cases (Mann-Whitney, p=0.022 and p=0.038, respectively). As PAX5 is essential to the immunoglobulin heavy chain DHJH to VHDHJH transition, we analyzed IGH rearrangement. No difference was detected regarding the frequency of IGH rearrangement (78% in normal vs. 74% in mutants) or the rearranged VH. Survival was not significantly different between the two groups of patients (log rank, p=0.45). In conclusion, PAX5 mutations were a frequent event in adult B-ALL, associated with BCR-ABL1 fusion gene but were not associated with a significant clinical evolution.

International audience; Deep learning models specifically CNNs have been used successfully in many tasks including medical image classification. CNN effectiveness depends on the availability of large training data set to train which is generally costly to obtain for new applications or new cases. However, there is a little concrete recommendation about training set creation. In this research, we analyze the impact of different class distributions in the training data to a CNN model. We consider the case of cancer detection task from histopathological images for cancer diagnosis and derive some useful hypotheses about the distribution of classes in the training data. We found that using all the training data leads to the best recall-precision trade-off, while training with a reduced number of examples from some classes, it is possible to inflect the model toward a desired accuracy on a given class.

Undifferentiated carcinoma of the nasopharyngeal type (UCNT) that histologically mimics Hodgkin's lymphoma (HL) ('Hodgkin's lymphoma-like UCNT' - HL-like UCNT) is known as a diagnostic pitfall. Using immunohistochemistry, Western blot and cDNA array technology, we wanted to document its phenotypical and molecular characteristics. We report herein 5 cases of UCNT that morphologically mimic HL and 3 classical UCNT cases. We compared the expression profiles of a thousand selected genes in HL-like UCNT and in classical UCNT cases. No difference in the profile of EBV infection was noted between the HL-like UCNT and control cases. Significant differences were detected in the expression of genes involved in the matrix modelling, angiogenesis, apoptosis and regulation of the Th-2 interleukins. The eosinophil chemoattractant eotaxin was expressed in the stroma of HL-like UCNT, but not in the control cases. The eotaxin receptor CCR3 was expressed in both stromal and carcinoma cell populations of HL-like UCNT, this pattern being similar to the one observed in HL. These results show that UCNT morphologically resembling HL share also some specific phenotypical and molecular features with HL, and might deserve to be isolated as a particular UCNT subtype.

Occasional EBV infection of human NK cells may lead to malignant diseases such as naso-pharyngeal NK lymphoma although NK cells do not express CD21, the primary receptor for EBV. Here we show that during early EBV infection in patients, NK cells attacked EBV-infected autologous B cells. In vitro, NK cells activated by conjugation to CD21+ B-EBV cell targets transiently acquired a weak CD21+ phenotype by synaptic transfer of few receptor molecules onto their own membrane. In the presence of viral particles, these ectopic receptors allowed EBV binding to the novel NK cell host. Hence, trans-synaptic acquisition of viral receptor from target cells might constitute an unsuspected mode of infection for otherwise unreachable lymphoid hosts.

We recently described a new gene, denominated human leukocyte formin (hlf), which was overexpressed in lymphoid malignancies and cancer cell lines. In contrast, a low expression of the hlf protein was observed in lymph node and peripheral blood leukocytes in normal tissues. Interestingly, the hlf protein associates with Akt, a protein kinase of an important pathway for cell survival. In order to better characterize the expression of the hlf protein we performed Western blotting in the lymphocytes isolated from 4 tonsils from adult patients obtained during routine tonsillectomy, at the Department of Hematology, Clinic Hospital, Barcelona. Results demonstrated that the CD19− cell population of the tonsil displayed a higher expression of this protein when compared with CD19+ cells. In addition, CD19+ cells were separated into two subpopulations: CD27+ (memory cells) and CD27− (naïve cells), and the CD19+/CD27+ cell presented a higher expression when compared with naïve B cells. Furthermore, we performed Western blotting analysis in frozen biopsies of non-Hodgkin’s lymphoma (NHL) patients obtained from the Department of Pathology, Purpan Hospital (Toulouse, France). The lymph node biopsies were performed at the time of clinical diagnosis and the initial diagnosis was confirmed by immunohistochemical analysis and classified according to REAL classification. Fifty-four patients were studied with ages ranging between 28 and 93 years (median 57 years). The histologic types were: 22 follicular NHL, 15 diffuse large B-cell NHL, 17 T cell NHL (non-otherwise specified). Five reactive lymph nodes were also studied. The expression of the hlf protein was detected in all lymphoma samples studied and also in the 5 reactive lymph nodes. The hlf expression, however, was higher in T cell NHL when compared with the others NHL and reactive lymph nodes (T cell NHL vs reactive lymph node, p=0.002; T cell NHL vs follicular NHL, p=0.0001; T cell NHL vs diffuse large B-cell, p=0.012; Mann Whitney test). The hlf protein may be involved in the anti-apoptosis mechanisms, as it is expressed in all types of lymphoproliferative samples and it is associated with Akt, a pathway that is constitutively activated in some hematologic malignancies. Indeed, the ortholog protein described in mice, presents a role in the protection of the cells from apoptosis, but the pathway is unknown. This report provides a more detailed description of the expression of hlf protein in normal lymphocytes and supports the hypothesis that the hlf protein has a role in the cancer molecular pathology of hematologic malignancies.

Deep convolutional neural networks excel at solving recognition problems in images. Recent advances in the field of digitisation of histological slides now make it possible to use these algorithms in real biomedical applications in microscopy. Automatic analysis solutions are therefore naturally developed to reduce diagnostic errors. We present two applications, one for the analysis of immunohistochemical markers, the other to assist in the diagnosis of lymphomas. Finally, we present the limits of deep learning to solve biomedical problems. This critique leads us to rethink deep learning as a support for data mining tools. By means of segmentation trees or subsumptions, these techniques, supported by deep learning, are compatible with human interpretation, economical in annotation and learning.; Les réseaux neuronaux convolutifs profonds excellent à résoudre les problèmes de reconnaissance dans les images. Les avancées récentes dans le domaine de la numérisation des lames histologiques permettent aujourd’hui d’utiliser ces algorithmes dans de véritables applications biomédicales en microscopie. Des solutions d’analyse automatiques sont donc naturellement développées pour réduire les erreurs de diagnostic. Nous présentons deux applications, l’une pour l’analyse de marquages immunohistochimiques, l’autre pour assister le diagnostic des lymphomes. Nous présentons enfin les limites de l’apprentissage profond pour résoudre les problématiques biomédicales. Cette critique conduit à repenser l’apprentissage profond comme un soutien aux outils de fouille de données. Par le biais d’arbres de segmentations ou de subsomptions, ces techniques, soutenues par l’apprentissage profond, sont compatibles avec l’interprétation humaine, économes en annotation et en apprentissage.

Long noncoding RNAs (lncRNAs) are defined as RNA transcripts that are larger than 200 nt but do not appear to have protein- coding potential. Recent studies have demonstrated that lncRNAs regulate many processes such as transcription, translation, cellular differentiation, gene expression regulation, cell cycle regulation, and chromatin modification. Cumulative evidence points towards an important role of lncRNAs in cancer initiation, development, and progression. However, our overall knowledge of lncRNAs in cancer, including leukemia, remains extremely limited. In this study, we investigated lncRNA expression by RNA-sequencing in 40 acute myeloid leukemia (AML) patients with normal karyotype. Among 11065 lncRNA expressed in our samples, we identified specific lncRNA signature associated with the presence of NPM1 mutation. To go further into the putative function of these lncRNAs, we used catRAPID Omics algorithm to predict potential protein partners. Interestingly, the majority of the selected lncRNAs contains putative SUZ12 binding sites, a PRC2 (Polycomb Repressive Complex 2) component known to be linked to lncRNAs and to epigenetically regulates target genes. By using SUZ12 RNA Immunoprecipitation, we identify one lncRNA named XLOC_087120 linked to SUZ12. XLOC_087120 is located in a region enriched in histone genes. Pearson correlation showed a significative anti-correlation between XLOC_087120 and histone neighboring coding gene expression suggesting a role of this lncRNA in the regulation of histone genes. The impact on histone genes expression was confirmed by overexpression and inhibition of XLOC_087120 in AML cell lines. Overexpression of NPM1 mutant in an AML cell line showed that NPM1 modulates the nuclear/cytoplasmic localization of XLOC_087120 and consequently its repressive function. Altogether, these data suggest that lncRNAs should be considered as key players in the pathogenesis of acute myeloid leukemias.; Les longs ARN non codants (lncRNAs) sont définis comme des transcrits de plus de 200nt et n'ayant pas de potentiel codant. Des études récentes ont démontré que les lncRNAs pouvaient être impliqués dans la régulation de la transcription, de la traduction, de la différenciation cellulaire, de l'expression génique, du cycle cellulaire et des modifications de la chromatine. De plus, il a été montré un impact fonctionnel de certains lncRNAs dans le processus de cancérogenèse mais nos connaissances actuelles sur ces molécules dans le cancer, et plus particulièrement dans la leucémie, restent extrêmement limitées. Au cours de cette étude, nous avons analysé l'expression des lncRNAs par RNA-sequencing sur 40 patients atteints de leucémie aiguë myéloblastique (LAM) à caryotype normal. Parmi les 11065 lncRNAs exprimés dans nos échantillons, nous avons identifié une signature de lncRNAs associée à la mutation de NPM1. Afin de mettre en évidence les fonctions putatives des lncRNAs sélectionnés, nous avons utilisé un algorithme de prédiction d'interaction protéine/ARN. De manière intéressante, plus de la moitié des lncRNAs présentent des sites d'interactions potentiels à SUZ12, une sous unité du complexe PRC2 (Polycomb repressive complex 2), connu pour être recruté par des lncRNAs pour la régulation épigénétique de gènes cibles. Par RNA immunoprécipitation (RIP) de SUZ12, nous avons pu démontrer que le lncRNA XLOC_087120 interagissait avec SUZ12. De plus, son expression est anti-corrélée avec celle des gènes voisins codants des histones, suggérant un rôle dans la régulation négative des histones par ce lncRNA. L'impact de la dérégulation de XLOC_087120 sur les histones a été confirmé par des expériences de surexpression et d'inhibition de ce lncRNA dans des lignées de LAM. De plus, même si la mutation NPM1 ne semble pas affecter directement l'expression de ce lncRNA, des expériences d'infection de la forme mutée de NPM1 dans une lignée LAM ont montré que NPM1 pourrait réguler la localisation nucléaire/cytoplasmique de XLOC_087120 et moduler sa fonction de répresseur. En conclusion, ces données suggèrent que les lncRNAs sont des facteurs clés dans la pathogenèse des LAMs.

L’édition de l’ARN consiste en une modification post-transcriptionnelle qui génère une séquence différente de celle de l’ADN génomique et contribue à la diversité du transcriptome et des protéines. La réaction d’édition la plus fréquente résulte de la conversion d’une adénosine en inosine, mécanisme catalysé par les enzymes ADAR1 et ADAR2 (adenosine deaminase acting on RNA). La dérégulation de ce processus est impliquée dans le développement et la progression tumorale de nombreux cancers tels que les glioblastomes ou les leucémies aiguës. Les objectifs de notre travail étaient de déterminer le rôle des enzymes ADAR dans l’établissement du phénotype tumoral à partir de l’analyse du transcriptome de 40 patients atteints de leucémie aiguë myéloblastique avec caryotype normal. Nous souhaitions également déterminer le niveau d’expression des enzymes ADAR à partir de plusieurs types de tumeurs hématopoïétiques issues de lignées cellulaires humaines.Nous avons mis en évidence une surexpression des isoformes d’ADAR1 et plus particulièrement d’ADAR1 p110 dans les lymphomes B et les LAL-B ainsi qu’une surexpression d’ADAR1 p110, ADAR1 p150 et ADAR2 dans les lymphomes T et les LAL-T. Nous avons également montré que les patients atteints de LAM avec un caryotype normal présentent des sites édités par les enzymes ADAR, essentiellement localisés au niveau des séquences non codantes, pour lesquelles aucune conséquence n’a pu être mise en évidence. Ainsi, l’analyse du transcriptome d’un nombre plus important de patients sera nécessaire pour identifier davantage de sites édités et améliorer la compréhension du rôle de ces protéines dans la leucémogenèse.