No description available.

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 5 uppsatser.

No description available.

No description available.

Primary gastrointestinal lymphoma is the most common type of extra-nodal lymphoma, representing about 30-50% of all extra-nodal involvement. The stomach is the most common site, with the colon and rectum accounting for a minority of occurrences. Primary colorectal lymphoma is uncommon, representing only 0.3% of all large intestinal malignancies and approximately 3% of GI lymphomas with the majority of these being B-cell non-Hodgkin lymphoma and diffuse large B-cell lymphoma (DLBCL) being the most common subtype. We present a case of an 85-year-old male who presented with symptoms suggestive of bowel obstruction, who after further evaluation was diagnosed with primary non-Hodgkin lymphoma of the colon, DLBCL subtype.

The present work concerns the regulation of B cell activation, growth and terminal differentiation of helper T cells. T cell dependent (TD) B cell activation requires physical cell to cell contact between competent helper T cells (TH) and B cells and the recognition of MHC Class II antigens. The involvement of immunoglobulin receptors in TD B cell induction and maturation of B cells to plasma cells, however, are still unclear. Long term helper T cell lines and clones were raised against naturally expressed minor transplantation antigens. Using such antigen specific TH lines and clones, the mechanisms controlling growth and maturation of B cells to plasma cells were studied. Specific TH cells against both H-Y and C3H/Tif "minor" antigens were able to polyclonally induce small, resting B lymphocytes to proliteration and high rate antibody secretion. This observation definitively excludes an obligatory role of membrane immunoglobulin molecules in TD B cell triggering. In contrast to other similarly derived TH clones, a variant clone, was isolated which was fully competent to activate B cells to proliferation but did not induce PFC in T cell depleted "target" spleen cells. This defect could, however, be fully reconstituted by cell culture supernatants derived from competent TH clones (but not from the variant clone). These results indicated the presence of two distinct factors in such supernatants, controlling either growth or maturation in TD B cell responses, and lead to further efforts in their characterization. A B cell growth factor (BSF-pI) derived from such supernatants, with a Mr of 15-20 kD, displayed no mitogenicity on small, resting B lymphocytes and failed to induce PFC in prol iterating B cells. On the other hand, two distinct species of B cell maturation factors (BMA) were separated from the supernatants with Mr of 60 kD and 30 kD, respectively. These factors induced PFC of several antibody isotypes in assays were only maturation activity was limiting, but only the 60 kD species induced Ig-secretion, in pure populations of lymphoma cells (WEHI-279.1). Finally, neonatal B cells were shown to be inducible to growth but not to immunoglobulin secretion by competent TH cells, in the absence of suppressive effects in the neonatal spleen cell population. These results suggest that "early" B lymphocytes are intrinsically defective in the reception or processing of maturation signals. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1984, härtill 5 uppsatser</p> / digitalisering@umu

BACKGROUND:Detection of B cell clonality is useful for assisting in the diagnosis of B cell lymphomas. Clonality assessment can be accomplished through evaluation of KAPPA and LAMBDA light chain expression. Currently, only slide based methods are available for the majority of patient biopsies and do not detect light chain protein or mRNA in many B-cell lymphomas. Herein we evaluated a new method, known as colorimetric in situ hybridization (CISH), with improved sensitivity and multiplexing capacity, for its usefulness in clonality detection in mature B cell malignancies.METHODS:The KAPPA and LAMBDA ISH was performed on a Ventana Benchmark XT utilizing two color chromogenetic detection. The probes comprised 2 haptenated riboprobes each approximately 500 base pairs long directed against the conserved regions of either KAPPA or LAMBDA mRNA. The dual colors consisted of silver deposition (black) for KAPPA light chain and a novel (pink) chromogen for LAMBDA light chain. Following optimization, CISH allowed visualization of mRNA in benign B cells in reactive tissues including germinal center, mantle zone, and post-germinal center cells. We then identified 79 cases of B cell lymphoma with formalin-fixed paraffin-embedded (FFPE) biopsies including: follicular (36 cases), mantle cell (6 cases), marginal zone (12 cases), lymphoplasmacytic (6 cases), small lymphocytic (4 cases), and diffuse large B cell (15 cases), which were selected on the basis of either prior flow cytometry or immunohistochemistry (IHC) results to serve as the predicate, "gold standard," comparator.RESULTS:39/79 (49.4%) cases were classified as KAPPA and 29/79 (36.7%) as LAMBDA light chain restricted / while 9/79 (11.3%) cases were classified as indeterminate. Of the 70 cases with KAPPA or LAMBDA light chain restricted CISH, 69/70 (98.6%) were concordant with the reference method, while 1/70 (1.4%) was discordant.CONCLUSIONS:Optimized CISH detected lower levels of mRNA than can be visualized with current slide based methods, making clonality assessment in FFPE biopsies possible for mature B cell neoplasms. In this preliminary study, CISH was highly accurate compared to flow cytometry or IHC. CISH offers the possibility of wider applicability of light chain ISH and is likely to become a useful diagnostic tool.Virtual Slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1430491067123856

Chronic lymphocytic leukemia (CLL) is a cancer of B cells and is the most common leukemia in North America. Current therapies are fraught with challenges, and drug resistance and disease relapse remain common occurrences. Therefore, novel therapies and novel therapeutic strategies are needed to improve CLL therapy. Better yet, therapies targeted at specific weaknesses of CLL cells will ensure maximum efficacy and minimum adverse toxicity. To this end, this thesis focuses on targeting the susceptible BCR pathway and lysosome-mediated cell death pathway using gefitinib and lysosomotropic agents, respectively. Firstly, the novel use of the tyrosine kinase inhibitor gefitinib was explored. This drug was most effective in aggressive ZAP-70+ CLL cells and cell lines. A similar inhibitor, erlotinib, had no effect in CLL. Gefitinib inhibited phosphorylation of Syk and ZAP-70, prevented downstream kinase activation, and supressed the pro-survival BCR response. ZAP-70 is implicated in the mechanism of action of gefitinib as introduction of ZAP-70 into a B cell line increased their sensitivity to gefitinib. Secondly, the novel strategy of targeting lysosomes was explored. The lysosomotropic drugs siramesine, nortriptyline, desipramine, mefloquine, and tafenoquine were all found to induce cytotoxicity and lysosome permeabilization. Lysosome permeabilization was accompanied with lipid peroxidation and followed by loss of mitochondrial membrane potential. Compared with healthy B cells, CLL cells were more sensitive to this cell death pathway. This was potentially due to the overexpression of SPP1 and overproduction of sphingosine, which destabilized lysosomes. Lastly, this thesis explored the clinical utility of these targeted therapies. Both gefitinib and siramesine were more effective in CLL cells than patient T cells. Furthermore, they retained efficacy amid protective stromal cells. Clinical correlations revealed that gefitinib and siramesine were effective in CLL cells with poor prognostic features. Siramesine was more effective in male cells and in previously-treated cells. Gefitinib was most effective in young patients. Overall, work presented herein demonstrates the efficacy of the tyrosine kinase inhibitor gefitinib and lysosomotropic agents in primary CLL cells. This work investigates the altered biology of the BCR pathway and lysosomes in CLL cells, and takes advantage of these weaknesses using targeted therapies. / October 2016

Proteolytic processing of transmembrane receptors and ligands can have dramatic effects on cell signaling and subsequent cellular responses. Previous studies demonstrated that a disintegrin and metalloproteinase 10 (ADAM10) may cleave numerous B cell-expressed receptors, including the low affinity IgE receptor (CD23). However, lethality of ADAM10-deficient embryos has limited examination of these cleavage events in lymphocytes. To investigate their role in B cell development and function, we generated B cell-specific ADAM10 knockout mice. Intriguingly, deletion prevented development of the entire marginal zone B cell (MZB) lineage. Further analysis revealed that ADAM10 is required for S2 cleavage of the Notch2 receptor and initiation of Notch2 signaling, which is required for MZB development. Additionally, cleavage of CD23 was dramatically impaired in ADAM10-deficient B cells. This finding and results of ex vivo cleavage assays demonstrated that ADAM10 is the principal in vivo sheddase of CD23. Previous studies have demonstrated that Notch signaling and CD23 cleavage regulate antibody production. Accordingly, deletion of ADAM10 profoundly inhibited germinal center formation, and T-dependent and T-independent antibody responses to immunization, implicating ADAM10 as a novel regulator of adaptive immunity. Additionally, to determine the role of ADAM10 activity in hematopoiesis, we generated transgenic mice (A10Tg) that overexpress the protease on lymphoid and myeloid progenitors. Surprisingly, this markedly suppressed B2 cell development and promoted dramatic expansion of myeloid-derived suppressor cells (MDSCs) via a cell intrinsic mechanism. A10Tg MDSCs inhibited T cell proliferation and adoptive immunotherapy of B16 melanoma, resulting in exacerbated metastatic progression that was prevented by MDSC depletion. Thus, A10Tg mice represent a novel model for the examination of MDSC development and MDSC-mediated immune suppression in a tumor-free environment. Finally, hematopoietic stem cell cultures revealed that ADAM10 overexpression directs myeloid development by dysregulating Notch signaling via uncoupling the highly regulated proteolysis of Notch receptors. Collectively, these findings demonstrate that ADAM10 is a critical regulator of Notch signaling, B cell development, and MDSC expansion. Moreover, they have important implications for the treatment of numerous CD23 and Notch mediated pathologies, ranging from allergy to cancer.

Lymphocyte activation and trafficking are indispensable to the immune system. CD44, an adhesion molecule, plays important roles in T cell activation, lymphocyte homing/trafficking, and tumor metastasis. Although the functions of CD44 have been shown in T cells and other leukocytes, little is known about its role in B cells. The effects of CD44 cross-linking on murine B cell activation via CD40L/IL-4 was explored using the anti-CD44 mAbs RK3G9 and IM7. Immobilized RK3G9 and IM7 could strongly inhibit B cell proliferation and Ig production, with IgE inhibition being prominent. Soluble anti-CD44 had no effect. The inhibitory effect of RK3G9 was not influenced by addition of anti-FCγRII, indicating no role for the inhibitory receptor. The effects of delayed addition of immobilized anti-CD44 mAbs were studied, and the results indicated no inhibition after 96 hrs of culture. B cells were also activated by either LPS or anti-IgM F(ab')2. While LPS-induced B cell activation was inhibited by immobilized anti-CD44 mAbs, anti-IgM activation was refractory. Interestingly, addition of both anti-IgM and CD40L or LPS resulted in some modulation of the inhibitory activity. Additionally, FACS and Elispot revealed that RK3G9-treated cells had reduced numbers of plasma cells. Taken together, these results suggest that CD44 cross-linking could control polyclonal B cell activation by CD40L, but allow sIgM/CD40L activation to continue.