Journal of neuroimmunology
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Primary fetal human astrocytes and an astrocytoma cell line, U373-MG, expressed membrane cofactor protein (CD46), CD59, and low levels of decay-accelerating factor (CD55). Astrocyte CD55 was capable of regulating C3 deposition on the cell surface; albeit at a lower level than primary human fibroblasts. Negligible complement-mediated lysis of primary astrocytes and the U373-MG cell line was observed, even when large amount of astrocyte-specific, complement-activating antibodies were bound to the cells. Blocking the function of CD59 on astrocytes resulted in a > 90% cell lysis, while equivalent lysis of fibroblasts could only be achieved with additional blocking of CD55.
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The present study investigated the effect of central administration of the prostaglandin of E2 type (PGE2) on the distribution of the immediate early gene (IEG) c-fos mRNA and the transcriptional activity of corticotropin-releasing factor (CRF) and its type 1 receptor in the brain of conscious rats. Adult male rats were sacrificed 30 min and 2 h after a single infusion of PGE2 into the right lateral ventricle (2 micrograms/10 microliters) and their brains cut from the olfactory bulb to the end of the medulla in 30 micrometer coronal sections. mRNAs encoding the IEG c-fos and CRF1 receptor were assayed by in situ hybridization histochemistry using 35S-labeled exonic riboprobes whereas the primary transcript (heteronuclear (hn)RNA) for CRF was detected using intronic probe technology as an index of CRF transcriptional activity. Colocalization of c-fos mRNA within CRF, vasopressin (AVP), and oxytocin (OT) neurons was determined by means of a combination of immunocytochemistry and in situ hybridization techniques on the same brain sections. ⋯ Central administration of PGE2 also induced expression of the CRF type 1 receptor in the parvocellular PVN. Taken together, these results provide clear anatomical evidence that central PGE2 injection causes specific and selective expression of c-fos in several brain structures recognized to be activated in the brains of endotoxin-challenged rats. It is therefore possible that PG of E2 type plays a crucial role within the CNS in the interface between the immune and nervous systems to modulate neuroendocrine responses, such as the hypothalamic-pituitary-adrenal axis.
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In vivo levels of interleukin-1 (IL-1) and IL-6, present in the interstitial spaces of brain, have been repeatedly monitored up to 7 days after insertion of a microdialysis probe, designed to induce mechanical trauma to the brain. IL-1 is barely detectable immediately after implantation but over a 24-48 h period a 15-fold increase is seen. In contrast IL-6 levels at day 0 are high, increasing slightly (10%) by day 1 but decreasing to 40% by day 2. ⋯ The astrocytic response to injury, evidenced by increased glial fibrillary acidic protein staining occurs much later, by day 7, and is unlikely to be responsible for IL-1 and IL-6 production found at 24-48 h. Since upon isolation and stimulation of microglia in vitro with lipopolysaccharide IL-1 and IL-6 can be measured in the supernatant, it would appear that they have the capacity to produce cytokines in vivo. Localised synthesis of cytokines at sites of brain injury by microglia would further stimulate microglia in an autocrine manner and also propagate the astrocytic reaction.
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Active opioid receptors have been solubilized from bovine striatal synaptosomal membranes and purified approximately 4000-fold using a combination of affinity and hydroxyapatite chromatography. The affinity column was constructed by attaching hybromet, a newly synthesized opioid ligand with high affinity for the mu receptor, to a solid support matrix. A polyclonal antibody was generated to opioid receptors by injection of the purified receptor preparation into female New Zealand rabbits. ⋯ By indirect immunofluorescence, the antibody was shown to bind specifically to the plasma membranes of the neurotumor cell line NCB-20 (neuroblastoma X Chinese hamster brain hybrid cells), which has high affinity opioid receptors. The observed fluorescence in the neuroblastoma cells was prevented by pre-adsorption of the antibody with purified receptor from rat brain. These results indicate that the antibody is specific for opioid receptors and may prove useful in the precise localization of opioid receptors in the central and peripheral nervous systems by immunohistochemical procedures.
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Expression of Class I (HLA-ABC) and Class II (HLA-Dr; Ia) major histocompatibility (MHC) antigens on endothelial cells and astrocytes was investigated in multiple sclerosis (MS) lesions of variable disease activity and in normal central nervous system (CNS) using immunocytochemical techniques. Findings were correlated to lesion pathology and to the presence and distribution of T cells, T cell subsets, and interleukin-2 (IL-2) receptor-bearing cells. HLA-ABC was present on virtually all endothelial cells in normal and pathologic tissue samples. ⋯ Expression of HLA-ABC and Ia molecules on astrocytes in MS lesions could indicate their involvement in local presentation of antigen to cytotoxic (T8+) and helper/inducer (T4+) T cells, respectively. The observed distinct distribution patterns of HLA-ABC and Ia-positive astrocytes might suggest that cytotoxic T8+ cells are operative early during lesion development in MS. This could be followed by a more extensive Class II MHC-restricted helper T cell-mediated immune response which leads to selective destruction of myelin via activated macrophages.