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Neutropenia is an almost constant feature of Chediak-Higashi syndrome (CHS). There is evidence for a central mechanism of neutropenia. Ultrastructural studies of the bone marrow from a child with CHS showed marked autophagia phenomena within myeloid precursor cells and mature neutrophils. Autophagic vacuoles were randomly distributed in the cytoplasm of the cells from the granulocytic series and some of them contained giant granules which thus appeared particularly resistant to the autophagic process. The vital cellular damage through endophagocytosis suggests the possibility of intramedullary destruction as an explanation for neutropenia.

Natural killer (NK) cell activity of unseparated peripheral blood mononuclear cells from 30 untreated patients with Hodgkin's disease and 22 age- and sex-matched normal controls was evaluated using the classical K 562 cells as targets. A significant defect was demonstrated in the patients with stage I-II and seemed to be more profound in patients with advanced disease (stage III-IV) and in those with B symptoms. The differences between subgroups of patients, however, were not statistically significant, mostly because of the wide dispersion of individual data. Pre-incubation of effector cells with alpha A leucocyte recombinant interferon led to a clear increase in NK cell activity in 4 of 6 patients tested, showing that depressed NK activity in Hodgkin's disease is still susceptible to the enhancing effect of interferon, at least in some patients.

The regulation and function of the CD44 family of surface glycoproteins were investigated in human monocyte-derived dendritic cells (DCs). Variant CD44 isoform transcripts encoding exons v3, v6, and v9 are differently regulated during the differentiation of monocytes into DCs. TNF-α treatment, which induces the maturation of DCs, up-regulates the expression of all v3-, v6-, and v9-containing isoforms examined. CD44 molecules are involved in the adhesion of DCs to immobilized hyaluronate (HA), and v3- and v6-containing variants participate in this function, whereas anti-CD44v9 mAbs were unable to inhibit DC adhesion to HA. The consequences of ligand binding to CD44 were examined by culturing DCs on dishes coated with HA or various anti-CD44 mAbs. HA, the anti-pan CD44 mAb J173, and mAbs directed against v6- and v9-containing (but not v3-containing) isoforms provoked DC aggregation, phenotypic and functional maturation, and the secretion of IL-8, TNF-α, IL-1β, and granulocyte-macrophage CSF. In addition, IL-6, IL-10, and IL-12 were released by DCs stimulated with either J173 or HA, although these cytokines were not detected or were found only at low levels in the culture supernatants of DCs treated with anti-CD44v6 or anti-CD44v9 mAbs. Our study points to distinct capacities of the v3-, v6-, and v9-containing isoforms expressed by human DCs to mediate cell adhesion to HA and/or a signal inducing DC maturation and the secretion of cytokines.

The so-called pseudo-acute abdomen has been reported in acute leukemia, both at diagnosis or relapse. The clinical presentation may be misleading and life-threatening, due to the possible infiltration of any abdominal viscera. The authors present a series of eight patients and emphasize the management specificities of such patients and the possibility of long-term remissions, regardless of the severity of the initial presentation.

Like other viruses (i.e Epstein'Barr virus), the role of hepatitis C virus is suspected in the pathogenesis of lymphoproliferative disorders. We report one case of primary hepatic malignant lymphoma associated with chronic hepatitis C viral infection. The diagnosis was obtained by percutaneous liver biopsy showing a non-Hodgkin's diffuse large cell lymphoma and micronodular cirrhosis. Serology for hepatitis C virus positivity was known three years before lymphoma diagnosis. Staging of the lymphoma confirmed multinodular primary hepatic lymphoma with no other detectable localisation. Complete remission has been obtained with aggressive chemotherapy. The role of hepatitis C virus in the pathogenesis of the lymphoma is unknown. An indirect mechanism is suspected. Chronic inflammation may evolve from polyclonal lymphocytic proliferation to true non-Hodgkin's lymphoma, as it has been suggested for non-Hodgkin's lymphoma in the emergence of cryoglobulinemia in hepatitis C positive patients.

Cationic amphiphiles have been shown to mediate gene transfer to eukaryotic cells, although the nature and fate of the lipid-DNA complexes is still a matter of debate. Negative staining transmission electron microscopy (TEM) of the complexes in physiological medium, as well as thin-section TEM of transfected cells has been used to visualize the particles and the possible pathways leading to transgene expression. Lipopolyamines form a network of tubular micelles into which plasmid DNA is intertwined and condensed; the cationic particles contain hundreds of plasmid molecules and are heterogeneous with respect to size (0.1-0.5 microgram) and shape. Adherent cells (293M, 3T3, MRC5, primary leptomeningeal cells) take them up readily within minutes by spontaneous endocytosis. Among suspension cells, lymphocytes only incidentally show cytoplasmic inclusions and monocytes degrade the particles by phagocytosis. The marked decrease in transfection efficiency generally observed between adherent and nonadherent cells is thus due to reduce cell binding. This suggests that cationic particles bind to membrane components responsible for Ca2+-mediated cell anchoring to the extracellular matrix. Cation/anion-mediated endocytosis leads to endosomes that are entirely filled with the particles. Consequently, two escape mechanisms may operate: disruption of the lamellar envelope in close contact with tubular micelles, and endosome buffering by the lipopolyamine in response to proton entry, leading to osmotic swelling and endosome rupture. Even for moderately transfected MRC5 cells, 10(2)-10(3) particles are found either free or in cytoplasmic vacuoles 24 h after transfection, highlighting a very inefficient nuclear translocation process. Such high numbers are also the clue to the small concentration window between transfection and cytotoxicity that is often observed with nonviral vectors. Nuclear particle inclusions are sometimes seen, yet it is unclear whether plasmid uncoating (before expression) takes place by anion exchange in the cytoplasm or in the nucleus. The still lower efficiency of free plasmid translocation to the nucleus suggests an active role for the cationic lipid during this step. Although the last stages of the transfection mechanism remain unclear, the present work shows that the major barrier which hampers in vitro gene delivery with cationic vectors is nuclear translocation (and cell entry for nonadherent cells), providing precise targets for the design of improved nonviral vectors.

Cunninghamella bertholletiae is a fungus of the Zygomycetes class, Mucorales order. Only very few cases of disseminated infection have been reported. We observed a new case in a 19 years old man with severe aplastic anemia, due to pulmonary primoinfection and hematologic dissemination. This aplastic anemia failed to respond first to an antithymocyte globulin and steroid treatment and then to cyclosporine A. Deferoxamine was infused weekly to prevent iron overload. During a second antithymocyte globulin and steroid treatment, the patient developed bilateral pneumonia. Culture of the broncho-alveolar washing fluid established the diagnosis by isolation of C. bertholletiae. Despite amphotericin B and 5-fluorocytosine intravenous therapy, the patient died of disseminated infection six days after diagnosis, which was confirmed by necropsy. Underlying conditions, diagnosis and treatment are discussed, together with a review of the literature.