Purpose and Experimental Design: Loss of human leukocyte antigen (HLA) expression on tumor cells is frequent in diffuse large B-cell lymphoma (DLBCL) arising in immune-privileged sites, such as the testis and central nervous system, and is associated with small homozygous deletions of HLA-DQ/HLA-DR and larger hemizygous deletions of the MHC region. To better understand the significance of down-regulation of HLA class II expression in relation to the homozygous and hemizygous deletions, we analyzed global gene expression patterns in a series of 26 testicular DLBCL after characterization of these deletions. Results: Low levels of HLA-DR mRNA in whole testicular DLBCL samples were associated with a strong down-regulation of numerous immune-related genes specific for T cells, macrophages, antigen presentation and processing, lymphocyte activation, chemokines and chemokine receptors, and the complement system. The number of CD3 + tumor-infiltratingTcells was also significantly lower in low expressors of HLA-DR mRNA. Interestingly, hemizygous and homozygous deletions in the MHC region did not have any additional effect on global gene expression. Conclusion:In conclusion, we found that loss of HLA class II mRNA expression in testicular DLBCL is associated with a significant change in global gene expression patterns. This effect is independent of the mechanism causing the down-regulation of HLA class II genes in the lymphoma cells.Diffuse large B-cell lymphomas (DLBCL) are a heterogeneous group of non-Hodgkin's lymphomas, of which 40% present at extranodal sites. Many extranodal DLBCL behave clinically essentially different from nodal DLBCL. A subset of extranodal DLBCL arises in immune-privileged sites (IP-DLBCL), such as the central nervous system or the testis. Among the extranodal DLBCL, testicular DLBCL stand out with a characteristic high relapse rate to the central nervous system and contralateral testis (1) and a very poor prognosis. In addition, patients with a low-risk International Prognostic Index have a very poor outcome (2).We previously described the loss of HLA class I and II expression on tumor cells in >50% of the primary IP-DLBCL of the testis and central nervous system (3 -6). In both IP-DLBCL subtypes, small homozygous deletions affected the HLA-DR and HLA-DQ genes, whereas larger hemizygous deletions affected the whole MHC region, including class I and III regions, as well. The specificity of this down-regulation in testicular DLBCL was confirmed in a recent immunohistochemical study on a large series of primary extranodal DLBCL presenting at various sites (7). In another recent study on predominantly primary nodal (non-IP) DLBCL, Rimsza et al. (8) showed that loss of expression of HLA class II is highly discriminative for the clinical behavior of the disease and by far the most significant single prognostic factor. Furthermore, loss of HLA-DR expression correlated with a low number of CD8 + T cells, suggesting that a presumed loss of tumor surveillance may have a negative effect on pati...

Diffuse large B-cell lymphomas (DLBCLs) constitute a heterogeneous group of lymphomas in which germinal centre B-cell-like and activated B-cell-like subtypes can be discerned based on pathology, clinical presentation, and gene expression patterns. Testicular DLBCLs form an immune-privileged site-related subgroup of DLBCLs with an unfavourable prognosis. In the present study, cDNA microarray analysis, immunohistochemistry for CD10, Bcl6 and MUM1, and somatic hypermutation analysis of the immunoglobulin heavy chain gene rearrangements were used to determine the subtype of primary testicular DLBCL. Immunohistochemistry revealed 14/22 testicular DLBCLs with an activated B-cell-like immunophenotype and 8/22 with an ambiguous immunophenotype co-expressing CD10 and high levels of MUM1. cDNA microarray analysis of these 22 and four additional cases showed a uniform activated B-cell-like gene expression pattern for both immunophenotypes. Somatic hypermutation analysis of immunoglobulin heavy chain genes showed a very high mutation load in seven cases tested, but intraclonal heterogeneity was found at low level in only one of these cases. It is concluded that primary testicular DLBCLs have uniform activated B-cell-like subtype characteristics despite a number of cases showing an ambiguous immunophenotype.

The sphingolipid composition and multidrug resistance status of three human neuroblastoma cell lines were established. SK-N-FI cells displayed high expression and functional (e¥ux) activity of P-glycoprotein, while multidrug resistancerelated protein 1 was relatively abundant and most active in SK-N-AS cells. These two cell lines exhibited higher sphingolipid levels, compared to SK-N-DZ, which had the lowest activity of either ATP-binding cassette transporter protein. SK-N-DZ cells also di¡ered in ganglioside composition with predominant expression of b-series gangliosides. In conclusion, these three neuroblastoma cell lines o¡er a good model system to study sphingolipid metabolism in relation to ATP-binding cassette transporter protein function. ß

Acute myeloid leukemia (AML) is a disease with a poor prognosis. It has been demonstrated that AML cells express the vascular endothelial growth factors, VEGFA and VEGFC, as well as kinase insert domain-containing receptor (VEGFR2), the main receptor for downstream effects, resulting in an autocrine pathway for cell survival. This study investigates the role of the VEGFR inhibitor PTK787/ZK 222584 in leukemic cell death, and the possibility of an additional effect on cell death by a chemotherapeutic drug, amsacrine. In three AML cell lines and 33 pediatric AML patient samples, we performed total cell-kill assays to determine the percentages of cell death achieved by PTK787/ZK 222584 and/or amsacrine. Both drugs induced AML cell death. Using a response surface analysis, we could show that, in cell lines as well as in primary AML blasts, an equal magnitude of leukemic cell death could be obtained when lower doses of the more toxic amsacrine were combined with low dosages of the less toxic VEGFR inhibitor. This study shows that PTK787/ZK 222584 might have more clinical potential in AML when combined with a chemotherapeutic drug such as amsacrine. In future, it will be interesting to study whether the complications and the long-term effects of chemotherapy can be reduced by lowering the dosages of amsacrine, and by replacing it with other drugs with lower toxicity profiles, such as PTK787/ZK 222584.