The small FOXP1 isoform predominantly expressed in activated B cell-like diffuse large B-cell lymphoma and full-length FOXP1 exert similar oncogenic and transcriptional activity in human B cells.

The forkhead transcription factor FOXP1 is generally regarded as an oncogene in activated B cell-like diffuse large B-cell lymphoma. Previous studies have suggested that a small isoform of FOXP1 rather than full-length FOXP1, may possess this oncogenic activity. Corroborating those studies, we herein show that activated B cell-like diffuse large B-cell lymphoma cell lines and primary activated B cell-like diffuse large B-cell lymphoma cells predominantly express a small FOXP1 isoform, and that the 5'-end of the gene is a common insertion site in murine lymphomas in leukemia virus- and transposon-mediated insertional mutagenesis screens.

B-Lymphoblastic Lymphomas Evolving from Follicular Lymphomas Co-Express Surrogate Light Chains and Mutated Gamma Heavy Chains.

Follicular lymphoma (FL) is an indolent B-cell non-Hodgkin lymphoma able to transform into germinal center-type diffuse large B-cell lymphoma. We describe four extraordinary cases of FL, which progressed to TdTCD20 precursor B-lymphoblastic lymphoma (B-LBL). Fluorescence in situ hybridization analysis showed that all four B-LBLs had acquired a MYC translocation on transformation.

Illegitimate WNT pathway activation by beta-catenin mutation or autocrine stimulation in T-cell malignancies.

Recent studies in mice have shown a role for the canonical WNT pathway in lymphocyte development. Because cancers often arise as a result of aberrant activation of signaling cascades that normally promote the self-renewal and expansion of their progenitor cells, we hypothesized that activation of the WNT pathway might contribute to the pathogenesis of lymphoproliferative disease. Therefore, we screened a large panel (n = 162) of non-Hodgkin lymphomas (NHL), including all major WHO categories, for nuclear expression of beta-catenin, a hallmark of "active" WNT signaling.

Stimulated plasmacytoid dendritic cells impair human T-cell development.

Thymic plasmacytoid dendritic cells (pDCs) are located predominantly in the medulla and at the corticomedullary junction, the entry site of bone marrow-derived multipotential precursor cells into the thymus, allowing for interactions between thymic pDCs and precursor cells. We demonstrate that in vitro-generated pDCs stimulated with CpG or virus impaired the development of human autologous CD34(+)CD1a(-) thymic progenitor cells into the T-cell lineage. Rescue by addition of neutralizing type I interferon (IFN) antibodies strongly implies that endogenously produced IFN-alpha/beta is responsible for this inhibitory effect.

No evidence for an association of ocular adnexal lymphoma with Chlamydia psittaci in a cohort of patients from the Netherlands.

Extra-nodal marginal zone B cell lymphomas (MZBCLs) of the mucosa-associated lymphoid tissues (MALT) arise at sites of chronic antigenic stimulation due to organ-specific autoimmunity or infections, like Helicobacter pylori-associated chronic gastritis and Borrelia burgdorferi dermatitis. Recently, conflicting data have been published regarding a possible association between Chlamydia psittaci and ocular adnexal MZBCL. In the present study, we analyzed a cohort of ocular adnexal MZBLs from the Netherlands for the presence of C.