Multifunctional cytokines in haemopoiesis

Down-regulation of MHC II in mesenchymal stem cells at high IFN-gamma can be partly explained by cytoplasmic retention of CIITA

Mesenchymal stem cells (MSCs) are located in postnatal bone marrow, show plasticity, are linked to various bone marrow disorders, exhibit phagocytosis, exert Ag-presenting properties (APC), and are immune suppressive. Unlike professional APCs, MSCs respond bimodally to IFN-gamma in MHC-II expression, with expression at 10 U/ml and baseline, and down-regulation at 100 U/ml. The effects at high IFN-gamma could not be explained by down-regulation of its receptor, IFN-gammaRI. In this study, we report on the mechanisms by which IFN-gamma regulates MHC-II expression in MSCs. Gel shift assay and Western blot analyses showed dose-dependent increases in activated STAT-1, indicating responsiveness by IFN-gammaRI. Western blots showed decreased intracellular MHC-II, which could not be explained by decreased transcription of the master regulator CIITA, based on RT-PCR and in situ immunofluorescence. Reporter gene assays with PIII and PIV CIITA promoters indicate constitutive expression of PIII in MSCs and a switch to PIV by IFN-gamma, indicating the presence of factors for effect promoter responses. We explained decreased MHC-II at the level of transcription because CIITA protein was observed in the cytosol and not in nuclei at high IFN-gamma level. The proline/serine/threonine region of CIITA showed significant decrease in phosphorylation at high IFN-gamma levels. An understanding of the bimodal effects could provide insights on bone marrow homeostasis, which could be extrapolated to MSC dysfunction in hematological disorders.

Immunomodulation of Bu-Zhong-Yi-Qi-Tang on in vitro granulocyte colony-stimulating-factor and tumor necrosis factor-alpha production by peripheral blood mononuclear cells

Bu-Zhong-Yi-Qi-Tang (BZYQT) is a Chinese medicine, and has been used for the treatment of hepatocellular carcinoma (HCC) patients. At present, we still do not fully understand the effects of BZYQT on the cellular physiology. Present in vitro study demonstrated that BZYQT is capable of increasing granulocyte colony-stimulating-factor (G-CSF) and tumor necrosis factor-alpha (TNF-alpha) production by peripheral blood mononuclear cells (PBMC) in healthy volunteers and patients with HCC. The productions of G-CSF and TNF-alpha by PBMC of volunteers were significantly stimulated by more than 125 microg/ml of BZYQT. G-CSF levels stimulated by PBMC of healthy volunteers were higher than in PBMC of the HCC patients when more than 625 microg/ml of BZYQT was administrated. The reason may be due to the impaired immunologic reactivity of mononuclear cells in HCC patients. However, the production levels of TNF-alpha in HCC patients can be stimulated to levels as high as those in healthy volunteers. When adding high concentration (3.125 mg/ml) of BZYQT to the cultured PBMC, the increments of G-CSF and TNF-alpha production decreased although there were no obvious changes in the number of metabolic active PBMC changed. TNF-alpha andG-CSF are known to play important roles in the biological defensive mechanism. These findings show that BZYQT is a unique formula for the stimulation of PBMC to produce G-CSF and TNF-alpha. Administration of BZYQT may be beneficial for patients with HCC to modulate these cytokines.

Expression and Function of the Type 3 Complement Receptor in Tissues of the Developing Mouse

Macrophage (Mφ) expression of the leukocyte integrins has been implicated in their adhesion and migration in the adult. Little is known, however, of the expression or function of these molecules during development. This study defines the spatial and temporal sequences of expression of the type 3 complement receptor (CR3) in the developing mouse; establishes the functional efficacy of this molecule in spreading, adhesion, and phagocytosis; and investigates its role in inflammatory and constitutive migration. Expression of CR3 on monocytes occurred early compared to Mφ-restricted glycoprotein F4/80, but expression on stellate tissue Mφ appeared later than F4/80 and was transient. Expression of CR3 on resident tissue Mφ is more widespread during development, being retained on only very specific Mφ populations in the adult. Neutrophil polymorphs expressed CR3 from day 17 of gestation onward. The anti-CR3 mAb 5C6 was used to investigate the role of CR3 in adhesion, spreading, and phagocytosis by neonatal Mφ. Neonatal macrophages were found to adhere, spread, and phagocytose by CR3-dependent mechanisms, and a CR3-independent system was implicated in the spreading of neonatal Mφ. The role of CR3 in migration during development was then investigated. 5C6 had potent effects on the early stages of the migration of myelomonocytic cells to an inflammatory stimulus in vivo. Despite efficient transplacental transfer of the Ab from pregnant mother to fetus, the process by which monocytes generate populations of resident tissue Mφ was undisrupted, indicating the existence of CR3-independent mechanisms of monocyte migration during development.

IFN-gamma, IL-6 and IL-4 modulate M. leprae- or PPD-specific cytotoxic T cells in leprosy patients

Specific cytotoxic T cells against intracellular pathogens may be generated in vitro. On the other hand it is well known that cytokines can regulate almost every aspect of immune function. The aim of this study was to evaluate the effect of some cytokines on the generation of cytotoxic T cells with specificity for Mycobacterium leprae- or PPD-pulsed autologous macrophages from leprosy patients and normal controls. Peripheral blood mononuclear cells from M. bovis BCG-immunized controls or from leprosy patients were stimulated with antigen, in the presence or absence of cytokines, for 7 days. These were used as effector cells in a 4-h [51Cr]-release assay. Our results show that development of cytotoxic T cells may be enhanced by gamma-IFN, IL-6 or the combination of IL-6 and IL-2. Addition of IL-2 or TNF-alpha alone did not modify the generation of cytotoxic activity. IL-4 down-regulated the cytotoxic response and gamma-IFN was able to counteract this effect. Hence, the generation of specific cytotoxic T cells can be modulated by cytokines. Whether this cytotoxic mechanism contributes to protection or tissue damage in M. leprae infection remains to be determined.

Selective splenic arteriography for interleukin-2 administration: radiologic complications from the initial 113 procedures

A retrospective analysis was performed of the safety and efficacy of selective splenic artery catheterization for infusion of the immunotherapeutic agent interleukin-2 (IL-2). Fifty-one patients with metastatic melanoma had 103 successful catheterizations out of 113 attempts (91%). In nine patients preferential contrast flow was obtained into the splenic artery. When satisfactorily placed, the catheter position remained stable during the period of infusion in 98% of examinations. The incidence of major arteriographic complications was 4.5% and of minor complications 8.9%. The main problems encountered were thrombosis (3.6%) or persistent bleeding/hematoma formation (2.7%), in a patient population at high risk of malignant coagulopathy. Subintimal contrast injection occurred in five examinations (4.5%).

Enhancing effects of human macrophage colony-stimulating factor on the secretion of human chorionic gonadotropin by human chorionic villous cells and tPA30-1 cells

Human macrophage colony-stimulating factor (hM-CSF) concentration-dependently enhanced the secretion of human chorionic gonadotropin (hCG) by primary cultured human cytotrophoblastic cells and a human placental cell line, 3A-SubE (tPA30-1). Since this effect appeared 12 hours after the addition of hM-CSF and disappeared when protein synthesis was inhibited, it was surmised that hCG synthesis was enhanced by hM-CSF. When anti fms (hM-CSF receptor) antibody was added, hCG secretion by cultured human cytotrophoblasts in early pregnancy markedly decreased. These findings demonstrate that hM-CSF acts on the chorionic villous cells and promotes hCG synthesis by these cells.