Transforming growth factor beta 1 directly and reversibly inhibits the initial cell divisions of long-term repopulating hematopoietic stem cells

Hematopoiesis appears to be regulated, in part, by a balance between extracellular positive and negative growth signals. Transforming growth factor beta-1 (TGF-beta 1) has been shown to be a negative regulator of primitive hematopoietic cells. This study examined the direct effect of TGF-beta 1 on the proliferation and differentiation of long-term repopulating hematopoietic stem cells (LTR-HSC) in vitro. We previously reported a cell fractionation approach that includes the selection of low Hoescht 33342/low Rhodamine 123 (low Ho/Rh) cell fractions that are highly enriched for long-term repopulating cells (LTR-HSC) and also clone to a very high efficiency in the presence of stem cell factor (SCF) + interleukin-3 (IL-3) + IL-6: 90% to 100% of individually cultured low Ho/Rh cells formed high proliferative potential clones. This high cloning efficiency of an LTR-HSC enriched cell population enabled proliferation inhibition studies to be more easily interpreted. In this report, we show that the continuous presence of TGF-beta 1 directly inhibits the cell division of essentially all low Ho/Rh cells (in a dose-dependent manner) during their 0 to 5th cell division in vitro. Therefore, it follows that TGF-beta 1 must directly inhibit the proliferation of LTR-HSC contained within these low Ho/Rh cells. The time required for some low Ho/Rh cells to undergo their first cell division in vitro was also prolonged in the presence of TGF-beta 1. Furthermore, when low Ho/Rh cells were exposed to TFG-beta 1 for varying lengths of time before neutralization of the TGF-beta 1 by monoclonal antibody, the ability to form macroclones was markedly decreased after approximately 4 days of TGF-beta 1 exposure. In addition, 1 to 10 ng/mL of TGF-beta 1 resulted in a maintenance of high proliferative potential-colony-forming cell (HPP-CFC) during 8 days of culture compared with loss of HPP-CFC in cultures with no added TGF- beta 1. In conclusion, this study shows that TGF-beta 1 directly inhibits the initial stages of proliferation of LTR-HSC and appears to slow the differentiation of daughter cells of low Ho/Rh cells.     

Granulomatous hepatitis caused by Bacillus Calmette-Guerin (BCG) infection after BCG bladder instillation.

BACKGROUND--Bladder instillations with Bacillus Calmette-Guerin (BCG) are commonly used as immunotherapy for bladder carcinoma. Sometimes patients experience serious systemic side effects, such as sepsis or pneumonitis. Granulomatous hepatitis is a rare serious side effect, which has been considered a hypersensitivity reaction to BCG. PATIENT--The first case of granulomatous hepatitis after BCG bladder instillation in which mycobacteria were identified by staining techniques and mycobacterial DNA was detected in liver tissue using the polymerase chain reaction is reported. CONCLUSION--The granulomatous hepatitis was caused by BCG infection of the liver after haematogenous dissemination of BCG, rather than hypersensitivity.     

Downregulation of proinflammatory cytokine release in whole blood from septic patients

Using animal models or healthy volunteers, injection of lipopolysaccharide (LPS) or bacteria causes activation of macrophages with excessive synthesis and secretion of proinflammatory cytokines. Although these models mimic the effects of LPS in the host, they may represent more of an experimental expression of endotoxemia than natural infection itself. Therefore, as an ex vivo model of sepsis, whole blood from 15 patients with severe sepsis and 20 control patients without infection was stimulated with LPS to study the kinetics of mRNA expression and release of proinflammatory cytokines, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, and IL-6. Stimulation of whole blood with 1 microgram/mL LPS resulted in a maximum increase of cytokine secretion in the control group, while a marked (P < .01) depression of TNF-alpha, IL-1 beta, and IL-6 release was observed in the septic group, which persisted up to 10 days after study enrollment. While IL-1 beta mRNA expression was similar in peripheral blood mononuclear cells (PBMCs) harvested from LPS-stimulated whole blood in septic and control patients, the half-life and consequently the expression of TNF-alpha and IL-6 mRNA were strongly reduced in the septic group. These data indicate a downregulatory mechanism of cytokine release in whole blood from patients with severe sepsis that occurs on different levels. Although excessive secretion of proinflammatory cytokines has been considered deleterious for the host, the reduced capacity of PBMCs in whole blood from septic patients to synthesize and secrete proinflammatory cytokines to an inflammatory stimulus may result in immunodeficiency, because these cytokines in low concentrations are involved in the upregulation of essential cellular and humoral immune functions.     

Acquired lysosomal storage caused by frequent plasmapheresis procedures with hydroxyethyl starch

BACKGROUND: Hydroxyethyl starch (HES) solutions have largely replaced conventional plasma expanders such as human albumin and colloidal fluids. Only a few side effects have been reported and mainly concern pruritus or blood coagulation disorders. Excessive HES exposure can result in diffuse tissue storage and accumulation with foamy appearing macrophages which produce the enzyme chitotriosidase (CT). In case of massive tissue storage, this enzyme activity can reach levels comparable to those of Gaucher disease. STUDY DESIGN AND METHODS: In this single-center retrospective analysis of 11 consecutive patients receiving large amounts of HES for chronic plasmapheresis, plasma CT activity was investigated. Five patients receiving chronic intermittent plasmapheresis with conventional plasma expanders served as controls. Plasma CT activity was measured and plotted against creatinine clearance. Where available, marrow aspirate was analyzed with light microscopy to detect foamy macrophages. One patient developed a lysosomal storage disease and was examined extensively. RESULTS: Conventional plasma expanders did not alter plasma CT activity. In patients with impaired renal function, frequent plasma replacement with HES resulted in an increase in plasma CT activity. In the patient with the acquired lysosomal storage disease, massive tissue infiltration with activated foamy macrophages was observed. The phagocytic capacity in this patient, however, did not seem to be altered. CONCLUSION: Patients with impaired renal function receiving large amounts of HES exhibit an increase in plasma CT activity. Because excessive HES exposure can result in an acquired lysosomal storage disease, this should be avoided in chronic plasmapheresis procedures.     

Prothrombotic coagulation abnormalities in patients with newly diagnosed multiple myeloma

Prothrombotic coagulation abnormalities were analyzed in patients with untreated multiple myeloma. Increases in factor VIII, in von Willebrand factor (vWF) and a decrease in protein S were observed and these changes were strongly associated with disease stage. No difference in baseline coagulation parameters was found between patients with and without subsequent venous thromboembolism.