Chromosomal breakpoints affecting immunoglobulin (IG) loci are recurrent in many subtypes of B-cell lymphomas. However, despite the predominant B-cell origin of the Hodgkin and Reed-Sternberg (HRS) cells in classical Hodgkin lymphoma (cHL), the presence of chromosomal translocations in IG loci has not yet been systematically explored. Therefore, we have investigated a series of cHL for chromosomal breakpoints in the IGH (n = 230), IGL (n = 139), and IGK (n = 138) loci by interphase cytogenetics. Breakpoints in the IGH, IGL, or IGK locus were observed in the HRS cells of 26 of 149 (17%), 2 of 70, and 1 of 77 evaluable cHLs, respectively. The IG partners could be identified in eight cHLs and involved chromosomal bands 2p16 (REL), 3q27 (BCL6, two cases), 8q24.1 (MYC), 14q24.3, 16p13.1, 17q12, and 19q13.2 (BCL3/RELB). In 65 of 85 (76%) cHLs evaluable for an IGH triple-color probe, the HRS cells showed evidence for a (partial) deletion of the IGH constant region, suggesting the presence of class switch recombination (CSR). Furthermore, analyses with this probe in cases with IGH breakpoints indicated that at least part of them seem to be derived from CSR defects. Our results show that chromosomal breakpoints affecting the IG loci are recurrent in cHL.

Diffuse large B-cell lymphoma (DLBCL) is more prevalent and more often fatal in HIV-infected patients and SIV-infected monkeys compared to immune-competent individuals. Molecular, biological, and immunological data indicate that virus-associated lymphomagenesis is similar in both infected hosts. To find genes specifically overexpressed in HIV/SIV-associated and non-HIV/SIV-associated DLBCL we compared gene expression profiles of HIV/SIV-related and non-HIV-related lymphomas using subtractive hybridization and Northern blot analysis. Our experimental approach allowed us to detect two genes (a-myb and pub) upregulated solely in HIV/SIV-associated DLBCLs potentially involved in virus-specific lymphomagenesis in human and monkey. Downregulation of the pub gene was observed in all non-HIV-associated lymphomas investigated. In addition, we have found genes upregulated in both non-HIV- and HIV-associated lymphomas. Among those were genes both with known (set, ND4, SMG-1) and unknown functions. In summary, we have demonstrated that simultaneous transcriptional upregulation of at least two genes (a-myb and pub) was specific for AIDS-associated lymphomas.

Multipotent mesenchymal stromal cells (MSCs) are an object of intense investigation due to their therapeutic potential. MSCs have been well studied in vitro, while their fate after implantation in vivo has been poorly analyzed. We studied the properties of MSCs from the bone marrow (BM-MSC) before and after implantation under the renal capsule using a mini pig model. Autologous BM-MSCs were implanted under the kidney capsule. After 2.5 months, ectopic foci containing bones, foci of ectopic hematopoiesis, bone marrow stromal cells and muscle cells formed. Small pieces of the implant were cultivated as a whole. The cells that migrated out from these implants were cultured, cloned, analyzed and were proven to meet the most of criteria for MSCs, therefore, they are designated as MSCs from the implant—IM-MSCs. The IM-MSC population demonstrated high proliferative potential, similar to BM-MSCs. IM-MSC clones did not respond to adipogenic differentiation inductors: 33% of clones did not differentiate, and 67% differentiated toward an osteogenic lineage. The BM-MSCs revealed functional heterogeneity after implantation under the renal capsule. The BM-MSC population consists of mesenchymal precursor cells of various degrees of differentiation, including stem cells. These newly discovered properties of mini pig BM-MSCs reveal new possibilities in terms of their manipulation.

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1879 Splenectomy in patients with MDS is a treatment option that is beeing applied very rare [Steensma D., et al, Leuk Res.,2003; Bourgeosis E., et al, Leukemia, 2001]. There are anecdotal reports with very few patients demonstrating its efficacy. In most cases splenectomy was indicated for MDS patients with immune related thrombocytopenia. Here we would like to report the results of 33 splenectomies in patients with MDS who have been treated in our Center during 1994–2010. Within this period of follow-up totally 155 patients were diagnosed with different forms of MDS, 35% of them presenting with hypoplasia. The MDS treatment algorithm in our Center incorporates splenectomy as one of the options for pts with hypoplastic forms of MDS with bone marrow blast count less than 10%, refractory to initial cyclosporin A treatment or refractory to transfusions. Among patients who were splenectomised there were 20 females, 13 males with a median age of 40 years (range 18–74). Median time from diagnosis to splenectomy was 12 months (range 4–107). By WHO-classification there were 2 patients with RA, 22 – with RCMD, 2 – with MDS and del (5q), 6 - with RAEB, 1 - with AML after MDS. Cytogenetic analysis was available in 32 cases, and karyotype was normal in 15 patients (47%).The most common abnormalities were: del (5q) - 3, del (20q) - 2, trisomy 8 - 2, tetrasomy 8 - 1, monosomy 7 - 2, complex karyotype - 4. Bone marrow biopsy revealed hypoplasia in 25 patients (75%), myelofibrosis – in 7 (21%). The median WBC count was 2,6*109/L (range 0,6-8,7), hemoglobin 6,9 g/dL (47-119) and platelets 26*109/L (6-170). 27 pts (82%) were RBC transfusion dependent, 22 (67%) - platelets transfusion dependent. 13 pts had received immunosuppression therapy (ATG, cyclosporine A) before splenectomy, 2 - cytotoxic chemotherapy, 3 - decitabine. The majority of splenectomies were done by laparoscopic method - 26 (79%), in one case the convertion was done. In all cases we performed liver biopsy. Postoperative complications (hemorrhage) occurred in 1 patient but there were no deaths due to operation. One death occurred in 7 days after splenectomy due to fulminant progression to AML. Median spleen weight was 180 gms (range 70–930). Median intraoperative blood loss was 250 ml (range 50–9350). Histology was available in 30 patients. Extramedullary hematopoesis was revealed in 3 cases (10%), blast infiltration - in 2 (7%), massive lymphoid infiltration was detected in 5 cases and in one patient in was proved to be clonal (marginal zone lymphoma, MZL). Hemosiderin depositions in the macrophages were seen in half of the cases -16 (53%). One case was characterized by granulomatosis in spleen and liver with negative immunohistohemical staining to Mycobacteria tuberculosis. Splenectomy lead to sustained improvement of cytopenias in 16 cases (48%): decreased transfusion dependence in 14 (42%) and transfusion independence in 2 (6%). After splenectomy 5 patients were followed by “wait and see” approach, 17 continued with immunosuppressive therapy (ATG,CyA), 3 patients were treated with cytotoxic chemotherapy, 1 – with decytabine, 2 received EPO, 1- danazol, 2 - iron chelation therapy, 2 – only transfusions therapy. We did not noticed the infections rate augmentation after splenectomy. Transformation to AML was registered 6 (18%) at median 6 months (0,3 -9). 13 splenectomized patients (39%) died at a median 12 months (range 0,3-84) and the main death reasons were: AML progression, aplasia deterioration followed by infections and hemorrhage. 20 patients are alive with a median follow-up after splenectomy 33 months (2-108). Analysis of our 15-years study data give us a confidence to conclude that splenectomy still may be an adequate option for distinct forms of MDS (hypoplastic forms with bone marrow blast count less than 10%, refractory to initial immunosupressive treatment or refractory to transfusions), producing cytopenia improvement in half of the patients with decreasing transfusion dependance also in half of the patients, sometimes bringing a clear diagnosis (MZL). The mechanism of action is not very clear but we can speculate that splenectomy removes the “cell-destroying” organ, deminishes immune pathways of cytopenias due to large lymphoid compartment deletion, provides the resustainment of sensitivity to immunosupressive agents. Disclosures: No relevant conflicts of interest to declare.