Efficient characterization of the TCR repertoire in lymph nodes by flow cytometry.

Analysis of the T-cell receptor (TCR) repertoire by flow cytometry proved to be relevant for investigating T-cell diversity and detecting reactive cells in blood samples. We used this approach to characterize non-malignant T-lymphocytes in lymph nodes and give insights into their origin. The TCR repertoire of CD4+ and CD8+ T-cells from 81 lymph nodes was analyzed with a four-color flow cytometer using a wide panel of 25 anti-Vbeta monoclonal antibodies. Flow cytometry proved to be a useful and informative technique. We demonstrated a diversified TCR-Vbeta repertoire, and only low level expansions, in 53% of the samples. They involved nearly all Vbeta families, were more frequent in the CD8+ subset of older patients, but were not related to pathology. No evidence could be demonstrated in favor of stimulation by common antigens. Interestingly, the TCR-Vbeta repertoire proved to be very similar in lymph nodes and blood samples. Our results argue that in the cases studied, lymph node enlargement is mainly due to an increased homing of circulating T-cells. They also provide reference values for expression of 25 TCR-Vbeta in lymph nodes, which could serve as a basis for further applications in diagnosis of T-cell lymphoproliferative disorders.

Tissue-type plasminogen activator has antiangiogenic properties without effect on tumor growth in a rat C6 glioma model.

Tissue-type plasminogen activator (tPA) plays a major role in the fibrinolytic system. According to several reports, tPA may also have antiangiogenic properties, especially in combination with a free sulfhydryl donor (FSD). In the rat C6 glioma model, in vitro and in vivo tPA synthesis by glioma cells is enhanced by differentiation therapy. To address the antiangiogenic potential of tPA in this model, tPA was overexpressed in glioma tumors by ex vivo transduction of C6 cells with a lentiviral vector encoding tPA. The transduced cells were subcutaneously implanted into nude mice. Gene transfer allowed for efficient synthesis of tPA by the C6 tumors. Although the treatment of tPA+ tumor-bearing animals with the FSD captopril generated angiostatin in situ and reduced endothelial vascularization of the tumors, it had no effect on tumor growth. Alternative mechanisms could account for this lack of effect and consequently have important implications for vascular the treatment of glioblastoma.

Genetics and epigenetics of 1q rearrangements in hematological malignancies.

Recently, we and others have described a novel class of chromosome aberrations that involves constitutive heterochromatin on human chromosome 1 (cytogenetic band 1q12). These anomalies are particularly frequent in B cell non-Hodgkins lymphoma (NHL) and multiple myeloma (MM) and, remarkably, almost invariably involve partial or total gain of chromosome 1q (including 1q12 heterochromatin) and the formation of novel heterochromatin/euchromatin junctions. This review discusses the pathological significance of these anomalies in light of i) recent integrated gene expression and array comparative genomic hybridisation (aCGH) profiling in MM and ii) increasing evidence of a key role for heterochromatin in the control of normal and pathological gene silencing.