Immunohistochemical Localization of Phosphorylated Glial Fibrillary Acidic Protein in the Prefrontal Cortex and Hippocampus from Patients with Schizophrenia, Bipolar Disorder, and Depression

Increasingly, abnormalities of glial cell function have been implicated in pathological studies of the major mental illnesses (schizophrenia, bipolar disorder, and major depression). In a recent proteomic study, four isoforms of astrocytic glial fibrillary acidic protein (GFAP) were decreased in one or more of these diseases. In the current study, we sought to determine the immunohistochemical localization of phosphorylated GFAP (pGFAP) in the prefrontal cortex and hippocampus and to describe possible disease-related changes in the distribution of pGFAP containing astrocytes. In the prefrontal cortex, interlaminar astrocytes in layer I and stellate astrocytes in layers II and VI were labeled. Labeled cells were also present adjacent to blood vessels in the gyral white matter and in underlying white matter generally. In the hippocampus, labeled cells were present in the polymorphic layer of the dentate gyrus. In the prefrontal cortex, schizophrenia and major depression were characterized by decreased labeling of astrocytes adjacent to blood vessels. There were no significant differences between the diagnostic groups in the other prefrontal layers or in the hippocampus. These results suggest that reduced numbers or functional regulation of pGFAP containing astrocytes occurs in schizophrenia and major depression. The mechanism by which this deficit occurs is not known, but it may adversely effect the regulation of neuronal metabolism, communication, and response to injury.     

FLT3 receptor expression on the surface of normal and malignant human hematopoietic cells

FLT3 ligand is a hematopoietic growth factor that plays a key role in growth of primitive hematopoietic cells. FLT3 receptor mRNA is found in early hematopoietic progenitors and in human myeloid leukemia blasts. Much less is known about the surface expression of FLT3 receptor on human hematopoietic cells. Using human 125I-FLT3 ligand, we have identified and characterized surface FLT3 receptors on normal and malignant human hematopoietic cells and cell lines. Our results showed that surface display of FLT3 receptor was greatest in fresh myeloid leukemia blast cells and myeloid leukemia cell lines. Erythroleukemic and megakaryocytic leukemia cell lines (n = 5) bound little to no 125I- FLT3 ligand. Scatchard analysis of 125I-FLT3 ligand binding data shows that three myeloid leukemia cell lines, ML-1, AML-193, and HL-60, as well as normal human marrow mononuclear cells, exhibit high affinity FLT3 receptors. Crosslinking of 125I-FLT3 ligand to FLT3 receptors on the surface of ML-1 myeloid leukemia cells indicates that the FLT3 ligand. The rates of FLT3 ligand internalization and degradation were determined by binding 125I-FLT3 ligand to ML-1 cells and acid stripping to distinguish surface bound from internalized ligand. Internalized 125I-FLT3 ligand was detected within 5 minutes after binding to ML-1 cells. In addition, we evaluated the effect of FLT3 ligand on megakaryocytic colony growth and nuclear endoreduplication, alone or in the presence of thrombopoietin. FLT3 ligand did not promote colony forming unit megakaryocyte (CFU-Meg) colony growth or megakaryocyte nuclear maturation, nor did FLT3 ligand augment the effects of thrombopoietin on these measures of megakaryopoiesis. These data indicate that the FLT3 receptor shares several characteristics with the c-kit receptor including dimerization and rapid internalization. However, the more restricted cellular distribution of the FLT3 receptor may target the effects of FLT3 ligand to primitive hematopoietic cells and to myeloid and lymphoid progenitor cells, in contrast to the pleiotropic effects of the c-kit receptor ligand, stem cell factor.     

Stem cell factor modulates avidity of alpha 4 beta 1 and alpha 5 beta 1 integrins expressed on hematopoietic cell lines

Interactions between hematopoietic cells and bone marrow (BM) stroma, composed of extracellular matrix and stromal cells, are crucial for hematopoiesis. Integrins facilitate these interactions by mediating adherence of hematopoiesis. Integrins facilitate these interactions by mediating adherence of hematopoietic cells to both the extracellular matrix and stromal cells. Marrow stromal cells secrete a variety of growth factors, including stem cell factor (SCF). Because treatment with SCF in vivo mobilizes primitive hematopoietic cells from the BM, we investigated the effect of the growth factor SCF of hematopoietic cell adhesion. These studies show that SCF modulates adhesive function in a dose- and time-dependent manner, but does not modulate expression of the integrins alpha 4 beta 1 and alpha 5 beta 1 in the SCF- responsive cell line MO7E. Treatment of MO7E cells with SCF (200 ng/mL) produced a transient increase in adherence to cytokine-activated human umbilical vein endothelial cells (HUVECs) or to vascular cell adhesion molecule 1 (VCAM-1)-transfected Chinese hamster ovary (CHO) cells with peak adhesion at 30 minutes and return to baseline by 60 to 90 minutes. This increase in adhesion was paralleled by increased binding of the beta 1 activation-dependent monoclonal antibody (MoAb) 15/7, as determined by flow cytometry. However, prolonged incubation of MO7E with SCF induced a marked decrease in integrin-mediated adherence, with maximal inhibition by 24 hours. No change in expression of integrins, as determined by flow cytometry, was observed with short- or long-term incubation with SCF. SCF-treated cells were still able to respond to phorbol esters and to the activating beta 1 MoAb 8A2 with increased adherence, but not to the level seen in control cells. This suggests that a subpopulation of expressed alpha 4 beta 1 and alpha 5 beta 1 integrins is disengaged by prolonged incubation with SCF.     

Protein A adsorption of acute myelogenous leukemia serum induces in vitro blast lysis

We studied cytotoxic activity of acute myelogenous leukemia (AML) sera for AML blasts before and after immunoadsorption with Staphylococcus aureus, Cowan I (SAC), which contains protein A. We found in vitro that incubation with treated AML sera reduced viability to 42.7% of control (p less than 0.01) for autologous and 21.0% of control (p less than 0.01) for allogeneic blasts. Normal peripheral blood cells were not killed by treated AML sera. Wood 46 strain of Staphylococcus aureus, which does not contain protein A, did not significantly reduce AML blast viability (94.8%, p greater than 0.4), while Sepharose-bound protein A reduced viability to 63.8% (p less than 0.01). Cytotoxicity does not appear to be complement-mediated, byt cytotoxic activity is trypsin-sensitive and is contained in the immunoglobulin fraction. This model for study of the tumoricidal action of protein A adsorption should be useful for predicting utility of plasma adsorption as a therapeutic adjunct in the future.     

Sarcoidosis: correlation of extent of disease at CT with clinical, functional, and radiographic findings

Computed tomography (CT) was compared with chest radiography in the assessment of disease severity in 27 patients with sarcoidosis. The CT scans and radiographs were each read twice by two independent observers. Disease extent was assessed on CT scans by visual scoring (0%-100% involvement of the lung parenchyma) and on radiographs by using an adaptation of the International Labour Office classification. The severity of parenchymal changes on the CT scan and on the radiograph was significantly correlated with the severity of dyspnea (r = .61 and .58, respectively; P less than .001), diffusing capacity (r = -.62 and -.52, P less than .01), and vital capacity (r = -.49 and -.51, P less than .01). Patients with predominantly irregular opacities had more severe dyspnea and lower lung volumes than patients with predominantly nodular opacities (P less than .05). The authors conclude that in patients with sarcoidosis, the radiographic and CT assessments of disease severity show similar correlation with clinical and functional impairment.