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Caspase 10 (Mch4/FLICE2) is a caspase homologous to caspase 8. A recent report described that inherited CASP10 gene mutations underlie defective lymphocyte and dendritic cell apoptosis in autoimmune lymphoproliferative syndrome (ALPS). In this study, to explore the possibility that mutation of this gene might be involved in the development of non-Hodgkin lymphoma (NHL), we have analyzed the entire coding region and all splice sites of the CASP10gene for the detection of somatic mutations in 117 human NHLs. Overall, 17 NHLs (14.5%) were found to have CASP10mutations, which were identified in the coding regions of the prodomain (n = 3), the p17 large protease subunit (n = 11), and the p12 small protease subunit (n = 3). We expressed the tumor-derived caspase 10 mutants in 293 cells and found that apoptosis was suppressed. These data suggest that the inactivating mutations of theCASP10 gene might lead to the loss of its apoptotic function and contribute to the pathogenesis of some human NHLs.

Background: Clamydophila psittaci (C. psittaci) has been proposed as an etiologic factor for extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in the ocular region. However, previous studies showed varied association rates ranging 0% to 87%, not constant even in the series of same geographical areas, which suggest that there could be some technical variance in detecting methods for C. psittaci. The authors validated five sets of primers for detecting C. psittaci DNA and investigated its association with ocular MALT lymphomagenesis. Material and Methods: Five sets of PCR primers including 4 previously reported and one newly designed were evaluated with positive control C. psittaci DNA (acquired from Korea Centers for Disease Control and Prevention). One hundred fifty cases of confirmed ocular MALT lymphomas were collected from pathology archives of our institutes from 2008 to 2014, and entered into this study. DNA was extracted from archival paraffin block sections with Qiagen DNA extraction kits. Quality of DNA was assessed with NanoDrop and beta-globin PCR. Standard PCR was performed together with negative (H2O and tonsil DNA) and positive control C. psittaci DNA. Results: In all five primer sets for C. psittaci DNA, each PCR product showed clear positive band and negative with appropriate positive and negative controls, respectively. All 150 ocular MALT lymphoma cases showed positive for Beta-globin DNA control, but negative for C. psittaci DNA in any of PCR product with five primer sets. Conclusion: These results suggest that possibility of the pathogenetic role of C. psittaci in ocular MALT lymphoma would have been overestimated so far, at least in Korean people. Disclosures No relevant conflicts of interest to declare.

Abstract 5195 High-grade lymphomas are aggressive but largely curable, whereas low-grade lymphomas are indolent, but frequently recur to be incurable, paradoxically. Mesenchymal stromal cells (MSCs) have been known to participate for reconstituting microenvironment. Studies show that signalings between normal lymphoid cells and stromal cells were frequently altered in high grade lymphomas, but relatively conserved in low grade lymphomas. However, which cell and mechanism is responsible for lymphoma recurrence remains unclear. Here we hypothesized that the interaction with stroma may play a role for lymphoma cell growth and survival. For this, we investigated the effect of MSCs on lymphoma cell growth and chemo-resistance by using a coculture system with MSCs (derived from tonsil), as a stromal microenvironment for lymphoma cells. First, coculture of lymphoma cell line (Pfeiffer) and primary lymphoma cells with/without MSCs for 3 days showed that the MSC-cocultured cells grew more rapidly (1.4 times and 1.8 times for Pfeiffer and primary cells, respectively) than MSC-free lymphoma cells. To further investigate the underlying mechanism of promoting growth, lymphoma cells were cocultured with MSCs in the presence or absence of transwell filter. At day 4, the proliferation of lymphoma cells in the absence of transwell was 3.5 times higher than in the presence of transwell. Interestingly, the lymphoma cells cocultured with MSCs showed increased expression of CXCR4 compared with lymphoma cells cultured alone. When the cyto-protective effect of MSCs was examined by doxorubicin treatment (1ug/ml) in the presence or absence of MSCs, 91% of MSC-cocultured cells survived, whereas only 28% of stroma-free cultured cells survived. These results demonstrate that the direct contact interaction with stroma might be important for lymphoma cell growth and survival. In conclusion, our data suggest that the interaction with stromal microenvironment is an important factor for survival of lymphoma cells which cells might be responsible for chemoresistance, and raise the possibility that the stromal interaction could be a potential target for lymphoma treatment. Disclosures: No relevant conflicts of interest to declare. This research was supported by a grant (10172KFDA993) from Korea Food & Drug Administration in 2011. Disclosures: No relevant conflicts of interest to declare.

Intestinal TMA, a upcoming and serious problem after HSCT, usually manifests diarrhea, vomiting, GI bleeding and abdominal pain as initial clinical presentations similar to those of intestinal GVHD. But intestinal TMA should be distinguished from GVHD, because they needed to be treated in absolutely different way. Here we investigated the incidence of intestinal TMA and evaluated their clinical progressions in HSCT patients. We retrospectively reviewed 243 gastrointestinal mucosal biopsy slides obtained from HSCT patients having suffered from GI problems in the Catholic University Hospital, from 2000 to 2004. The collected cases were reviewed by two pathologists blindly and classified into TMA; showing microthrombi formation in the lumina of microvasculatures, GVHD; showing epithelial apoptosis and/or loss of glands, TMA+GVHD and non-specific inflammation. And next, their incidence and clinical outcomes were analyzed. On histopathological examination, 15 out of 243 cases (6.2%) showed luminal thrombi of microvasculature compatible with TMA, 58 cases (23.9%) showed findings compatible with GVHD, 3 cases (1.2%) showed both TMA and GVHD, and 173 cases (71.2%) showed nonspecific gastroenteritis. On peripheral blood smear examination, all 15 TMA cases showed less than 1% of fragmented RBC at the time of biopsy. But 2 out of 15 cases (13.3%) showed increase to 8% and 10% of fragmented RBC in follow-up, and they had been aggravated clinically and improved only after treatments including discontinuing immunosuppressant and plasma exchange. Among 58 GVHDs, 34 patients (75.9%) were improved with steroid pulse therapy, but 14 patients (24.1%) failed. These results show that intestinal TMA is not infrequent in HSCT patients and can be combined with intestinal GVHD. In conclusion, intestinal TMA should be recognized in pathological diagnosis of HSCT patients. It is important to differentiate intestinal TMA from GVHD in patients suffering from severe and refractory diarrhea after HSCT.

Follicular dendritic cell neoplasm(FDCN), a rare tumor exhibiting a broad histopathological spectrum and unpredictable biologic behavior, has been classified into follicular dendritic cell tumor(FDCT) and follicular dendritic cell sarcoma(FDCS) regarded as borderline lesion and malignant tumor, respectively, by World Health Organization. But still no definite diagnostic criteria distinguishing FDCT from FDCS was established. Here in, as an approach to the differential diagnostic criteria, we performed clinicopathological analysis for 146 cases of FDCN, documented in English literature from January 1986 to May 2006. Through PubMED search with key words of FDC or dendritic cell tumor, we collected and reviewed 73 articles out of more than six thousands candidates, which contained 146 FDCNs with clinicopathological informations. We analyzed the carefully selected cases with parameters including age, gender, tumor location, tumor size, tumor margin, EBV association, mitosis, nuclear atypism, hemorrhage, necrosis and Castleman’s disease association. Recurrence, metastasis and death of disease were referred as event. Kaplan-Meier model was used for overall event-free survival analysis and the log-rank test was used to assess statistical significance. Mitotic Index (MI, ≥ 5/10HPF vs

Cancer stem cells are subpopulations of cancer cells with potential to seed and develop new cancer mass causing recurrence and/or metastasis, but phenotypic characteristics of such cell populations remains uncertain. As an initial approach to identify heterogeneity in cancer mass, we performed comparative study using matched pairs of primary breast cancer masses and their immediate metastatic counterparts in regional LN. First, in the gene expression study of primary tumor mass and their LN counterpart using cDNA microarray, about 100 genes showed differential expression between the two, but with variations depending on cases (3 Exp). In addition, when fresh individually matched surgical block from primary mass and LN mass were each inoculated into NOD/SCID mice, higher growth of LN-derived mass was observed supporting distinction between the two (2 Exp). In subsequent search for phenotypic difference between the two, 99 primary-LN tissue pairs with individual matching were immunostained for CD24, a newly proposed marker for cancer stem cell, and analysed by semiquantitative scoring (0, 1+, 2+, 3+, 4+). Among 73 cases with positive staining for CD24, higher level of CD24 expression in LN mass compared to its matched primary tumor tissue was observed in 38 cases (52.1%), while the opposite was for only 7 cases (9.6%). Furthermore, high level expression (4+) of CD24 was observed more frequently in LN tumor tissues (63.0%, 46/73) than in their primary tumor counterparts (26%, 19/73)( P = 0.000). These results support the notion that cancer cells in tumor mass are clonally heterogeneous and suggest that CD24 expression could be related to characteristic of metastatic cancer stem cells.