Immunocytochemical method to identify myelin basic protein in oligodendroglia and myelin sheaths of the human nervous system

Total Chemical Syntheses of the GM3 and F-GM3 Ganglioside Epitopes and Comparative Pre-Clinical Evaluation for Non-Invasive Imaging of Oligodendrocyte Differentiation

Gangliosides are intimately involved in a plenum of (neuro)inflammatory processes, yet progress in establishing structure-function interplay is frequently hindered by the availability of well-defined glycostructures. Motivated by the ubiquity of the ganglioside GM₃ in chemical neurology, and in particular by its conspicuous presence in myelin, the GM₃ epitope was examined with a view to preclinical validation as a tracer. The suitability of this scaffold for the noninvasive imaging of oligodendrocyte differentiation in Multiple sclerosis is disclosed. The stereocontrolled synthesis of a site-selectively fluorinated analogue (F-GM₃) is also disclosed to enable a comparative analysis in oligodendrocyte (OL) differentiation. Whereas the native epitope caused a decrease in the viability in a dose-dependent manner, the addition of distinct F-GM₃ concentrations over 48 h had no impact on the OL viability. This is likely a consequence of the enhanced hydrolytic stability imparted by the fluorination and highlights the potential of fluorinated glycostructures in the field of molecular imaging. Given the predominant expression of GM₃ in oligodendrocytes and the capacity of GM₃ to interact with myelin-associated proteins, this preclinical evaluation has revealed F-GM₃ to be an intriguing candidate for neurological imaging.

Regulation of auditory plasticity during critical periods and following hearing loss

Sensory input has profound effects on neuronal organization and sensory maps in the brain. The mechanisms regulating plasticity of the auditory pathway have been revealed by examining the consequences of altered auditory input during both developmental critical periods—when plasticity facilitates the optimization of neural circuits in concert with the external environment—and in adulthood—when hearing loss is linked to the generation of tinnitus. In this review, we summarize research identifying the molecular, cellular, and circuit-level mechanisms regulating neuronal organization and tonotopic map plasticity during developmental critical periods and in adulthood. These mechanisms are shared in both the juvenile and adult brain and along the length of the auditory pathway, where they serve to regulate disinhibitory networks, synaptic structure and function, as well as structural barriers to plasticity. Regulation of plasticity also involves both neuromodulatory circuits, which link plasticity with learning and attention, as well as ascending and descending auditory circuits, which link the auditory cortex and lower structures. Further work identifying the interplay of molecular and cellular mechanisms associating hearing loss-induced plasticity with tinnitus will continue to advance our understanding of this disorder and lead to new approaches to its treatment.

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During CPs, brain plasticity is enhanced and sensitive to acoustic experience.

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Enhanced plasticity can be reinstated in the adult brain following hearing loss.

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Molecular, cellular, and circuit-level mechanisms regulate CP and adult plasticity.

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Plasticity resulting from hearing loss may contribute to the emergence of tinnitus.

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Modifying plasticity in the adult brain may offer new treatments for tinnitus.

Shaping the aging brain: role of auditory input patterns in the emergence of auditory cortical impairments

Age-related impairments in the primary auditory cortex (A1) include poor tuning selectivity, neural desynchronization, and degraded responses to low-probability sounds. These changes have been largely attributed to reduced inhibition in the aged brain, and are thought to contribute to substantial hearing impairment in both humans and animals. Since many of these changes can be partially reversed with auditory training, it has been speculated that they might not be purely degenerative, but might rather represent negative plastic adjustments to noisy or distorted auditory signals reaching the brain. To test this hypothesis, we examined the impact of exposing young adult rats to 8 weeks of low-grade broadband noise on several aspects of A1 function and structure. We then characterized the same A1 elements in aging rats for comparison. We found that the impact of noise exposure on A1 tuning selectivity, temporal processing of auditory signal and responses to oddball tones was almost indistinguishable from the effect of natural aging. Moreover, noise exposure resulted in a reduction in the population of parvalbumin inhibitory interneurons and cortical myelin as previously documented in the aged group. Most of these changes reversed after returning the rats to a quiet environment. These results support the hypothesis that age-related changes in A1 have a strong activity-dependent component and indicate that the presence or absence of clear auditory input patterns might be a key factor in sustaining adult A1 function.

Immunohistological localization of the myelinating cell-specific receptor LP(A1)

LP(A1) (also termed Edg-2 or VZG-1) is a G-protein-coupled receptor for lysophosphatidic acid and its gene transcripts have been found selectively expressed by mature myelin-producing cells. We have raised in rabbit a polyclonal antibody against a sequence unique to LP(A1) and common to rat, mouse, and human orthologues. In Western blots, LP(A1) immunoreactivity appeared as 44-53 kDa bands in extracts from recombinant RH7777 cells expressing LP(A1), mouse purified oligodendrocytes, or human white matter, but not from wild-type RH7777 cells or purified astrocytes. In glial cultures, LP(A1) immunoreactivity was restricted to oligodendrocytes, appeared at cell membrane and processes, colocalized with myelin basic protein, and appeared before myelin/oligodendrocyte glycoprotein. In slices of rat and human brains, LP(A1) immunoreactivity was found in myelinated tracts, as well as in oligodendrocyte somata and their myelinating fibers. Immunoreactivities of LP(A1) and myelin basic protein colocalized in the brain, but oligodendrocyte soma showed stronger signals for LP(A1) than myelinated fibers, whereas the reverse was true for myelin basic protein. These results strengthen the view that LP(A1) is involved in myelin formation or maintenance.

Association of increased bcl-2 expression with rescue from tumor necrosis factor-alpha-induced cell death in the oligodendrocyte cell line OLN-93

The present study investigated the effects of flupirtine (Katadolon) on tumor necrosis factor (TNF)-alpha-mediated cell death and Bcl-2 expression in the permanent rat oligodendrocyte cell line OLN-93 (OLN cells). TNF-alpha (500 U/ml) induced apoptosis of OLN cells, which was confirmed by DNA fragmentation using an in situ end-labeling technique and ultrastructural analysis. Flupirtine significantly reduced the rate of spontaneous cell death of OLN cells already at low concentrations; TNF-alpha-mediated apoptosis was suppressed only with higher concentrations of flupirtine (100 microM:). Expression of Bcl-2 protein and mRNA in OLN cells was detected by immunocytochemistry, western blot, and RT-PCR. Quantitative analysis of western blots revealed an approximately 2. 5-fold up-regulation of Bcl-2 protein during TNF-alpha treatment. Furthermore, addition of 10 or 100 microM: flupirtine before incubation with TNF-alpha led to an approximately threefold increase of Bcl-2 expression. Exposure of OLN cells to flupirtine alone moderately augmented the expression of Bcl-2 protein. Our data demonstrate that flupirtine up-regulates the expression of Bcl-2 protein in OLN cells; this Bcl-2 induction is associated with a reduced rate of TNF-alpha-induced cell death.

The Role of Immunohistochemistry in the Differential Diagnosis of Soft-Tissue Tumors

This regular feature presents special issues in oncologic pathology.

Hair cycle-dependent plasticity of skin and hair follicle innervation in normal murine skin

The innervation of normal, mature mammalian skin is widely thought to be constant. However, the extensive skin remodeling accompanying the transformation of hair follicles from resting stage through growth and regression back to resting (telogen-anagen-catagen-telogen) may also be associated with alteration of skin innervation. We, therefore, have investigated the innervation of the back skin of adolescent C57BL/6 mice at various stages of the depilation-induced hair cycle. By using antisera against neuronal (protein gene product 9.5 [PGP 9.5], neurofilament 150) and Schwann cell (S-100, myelin basic protein) markers, as well as against neural cell adhesion molecule (NCAM) and growth-associated protein-43 (GAP-43), we found a dramatic increase of single fibers within the dermis and subcutis during early anagen. This was paralleled by an increase in the number of anastomoses between the cutaneous nerve plexuses and by distinct changes in the nerve fiber supply of anagen vs. telogen hair follicles. The follicular isthmus, including the bulge, the seat of epithelial follicle stem cells, was found to be the most densely innervated skin area. Here, a defined subpopulation of nerve fibers increased in number during anagen and declined during catagen, accompanied by dynamic alterations in the expression of NCAM and GAP-43. Thus, our study provides evidence for a surprising degree of plasticity of murine skin innervation. Because hair cycle-associated tissue remodeling evidently is associated with tightly regulated sprouting and regression of nerve fibers, hair cycle-dependent alterations in murine skin and hair follicle innervation offer an intriguing model for studying the controlled rearrangement of neuronal networks in peripheral tissues under physiological conditions.

Immunohistochemical study of myelination and oligodendrocyte in infants with periventricular leukomalacia

Eighteen patients with periventricular leukomalacia (PVL) of the focal or widespread type were immunohistochemically studied with respect to myelination and ferritin-containing oligodendrocytes and compared with 23 controls. Morphometric examination of myelination and ferritin-containing oligodendrocytes revealed normal development in the nonnecrotic cerebral white matter of the focal PVL brains. Myelination was mainly impaired in the necrotic or gliotic periventricular white matter of the widespread PVL brains. The expression of lipid components was poorer than that of myelin basic protein and the number of ferritin-containing oligodendrocytes was decreased in the necrotic or diffuse gliotic region of the widespread PVL brains compared to the controls. There was a significant relationship between the number of ferritin-containing oligodendrocytes and the degree of myelination. The impaired myelination in the PVL brains occurred in the necrotic as well as gliotic regions in the cerebral white matter, and may be related to the decrease of normal oligodendrocytes.

Oligodendrocytes in the early course of multiple sclerosis

The neuropathology of demyelinating lesions in multiple sclerosis was studied in specimens obtained by diagnostic needle biopsy during early stages of the disease. The lesions were characterized by a chronic inflammatory reaction dominated by lymphocytes and macrophages, plaque-like demyelination, and astroglial sclerosis. Oligodendrocytes within the lesions were studied by immunocytochemistry using antibodies against various myelin and oligodendroglia components. The expression of messenger RNA for proteolipid protein was determined by in situ hybridization. Our studies revealed that myelin-oligodendrocyte glycoprotein is a sensitive and reliable marker for identification of oligodendrocytes in demyelinated plaques. The results suggest that in the early course of the disease in some patients, oligodendrocytes may largely be preserved, whereas in others oligodendroglial loss is pronounced. Loss of oligodendrocytes was only marginally related to the stage of demyelinating activity within the lesions. These findings indicate that the pathogenesis of demyelination may vary within different multiple sclerosis patients.

Cerebral white matter changes in acquired immunodeficiency syndrome dementia: alterations of the blood-brain barrier

The cause of acquired immunodeficiency syndrome (AIDS) dementia, which is a frequent late manifestation of human immunodeficiency virus (HIV) infection, is unknown but radiological and pathological studies have implicated alterations in subcortical white matter. To investigate the pathological basis of these white matter abnormalities, we performed an immunocytochemical and histological analysis of subcortical white matter from AIDS patients with and without dementia, from pre-AIDS patients (asymptomatic HIV-seropositive patients), and from HIV-seronegative control subjects. Reduced intensity of Luxol fast blue staining, designated "diffuse myelin pallor," was detected in 8 of 15 AIDS dementia patients, 3 of 13 AIDS nondemented patients, and none of the pre-AIDS patients (n = 2) or control subjects (n = 9). In contrast to Luxol fast blue staining, sections stained immunocytochemically for myelin proteins did not show decreased staining intensities in regions of diffuse myelin pallor. In addition, neither demyelinated axons nor active demyelination were detected in light and electron micrographs of subcortical white matter from brains of patients with AIDS dementia. An increase in the number of perivascular macrophages and hypertrophy of astrocytes and microglia occurred in brain sections from HIV-infected patients. These changes were not specific to dementia or regions of diffuse myelin pallor and they occurred in both gray and white matter. In contrast to the lack of myelin pathology in AIDS dementia brains, significant accumulations of serum proteins in white matter glia were detected in the brains of 12 of 12 patients with AIDS dementia and 6 of 12 AIDS patients without dementia. Serum protein-immunopositive cortical neurons were detected in the frontal cortex of 11 of 12 patients with AIDS dementia and 3 of 12 nondemented AIDS patients. Seronegative control subjects showed minimal serum protein immunoreactivity in both cortex and white matter. We conclude therefore that alterations in the blood-brain barrier and not demyelination contribute to the development of AIDS dementia.

Oligodendrogliomas: a clinical, histological, immunocytochemical and lectin-binding study

We have studied 27 oligodendrogliomas with a panel of antibodies (vimentin, GFAP, S-100 protein, myelin basic protein, CAM 5.2) and of lectins (WGA, Con A, PNA, RCA, DBA, SBA) to different glycoproteins. There were 16 well-differentiated tumours, including one gliofibrillary and 11 anaplastic oligodendrogliomas, three of which were gliofibrillary. Four cases showed positivity for vimentin, three of which were anaplastic tumours. Fifteen cases were positive for S-100 protein (nine well-differentiated and six anaplastic tumours) and 13 contained GFAP-positive cells (three well-differentiated and 10 anaplastic tumours). WGA binding was positive in 75% of well-differentiated and 63% of anaplastic oligodendrogliomas, the corresponding figures were 50% and 45% for PNA, 37% and 81% for Con-A and 25% and 54% for RCA. On the basis of the results with lectin binding, we believe that there are changes in the spectrum of tumour cell-associated lectin-like proteins during malignant transformation. Our observations also suggest that the pattern of lectin expression can undergo substantial changes in the course of differentiation.

Colocalization of lymphocytes bearing gamma delta T-cell receptor and heat shock protein hsp65+ oligodendrocytes in multiple sclerosis

The presence of T lymphocytes bearing the gamma delta T-cell receptor (TCR gamma delta) has been studied immunocyto-chemically in central nervous system (CNS) tissue from 13 patients with multiple sclerosis (MS), 4 with inflammatory non-MS CNS disorders, 6 with other neurological diseases, and 3 with nonneurologic conditions. Twenty-eight of 43 MS lesions contained TCR gamma delta cells and these were most frequently found in chronically demyelinated areas, in contrast to the previously studied CD4+, CD8+ (TCR alpha beta) population, which predominated in more active lesions. Some TCR gamma delta lymphocytes had an unusual morphology with long dendritic processes, which were sometimes interconnected forming a network. Because it is generally believed that TCR gamma delta lymphocytes function in a cytotoxic fashion in association with heat shock proteins (hsp), we examined the colocalization of TCR gamma delta cells with 65- and 70-kDa hsp (hsp65 and hsp70) in MS lesions. Hsp65 was expressed on immature oligodendrocytes at the margins of chronic lesions containing TCR gamma delta lymphocytes. The coexpression of these molecules might imply functional relationships perhaps of significance to the chronicity of the MS disease process and the failure of CNS remyelination.

Loss of white matter oligodendrocytes and astrocytes in progressive subcortical vascular encephalopathy of Binswanger type

To study whether oligodendrocytes and astrocytes can be affected in progressive subcortical vascular encephalopathy of Binswanger type (PSVE), the number of oligodendrocytes and astrocytes was counted in the white matter of frontal lobe. A sum of the number of oligodendrocytes and astrocytes in the deep white matter in PSVE accounted for approximately half of that in the age-matched controls. The number of oligodendrocytes, which were defined as the cells with small, round and solid nuclei in the present study, also decreased in PSVE showing half of that in the deep white matter of the controls. The present data suggest that the loss of oligodendrocytes and astrocytes can play a role to the process of nerve fibres loss in PSVE, which has been reported in my previous study (1), although the possibility that nerve fibres loss results in the secondary loss of oligodendrocytes can not be ruled out.

Neurobiology of human oligodendrocytes in culture

Enriched populations of oligodendrocytes were isolated from adult human brains of 3-15 hours postmortem using the trypsinin digestion-Percoll density gradient method and were cultured for an extended period of time up to 6 months. Cell type specific antigens that were expressed by oligodendrocytes were galactocerebroside, myelin basic protein, proteolipid protein, 2'3'-cyclic nucleotide 3'-phosphohydrolase and myelin-associated glycoprotein. In addition, HLA-A,B,C and HLA-DR, respectively, Class I and Class II antigens of the major histocompatibility complex, were demonstrated on oligodendrocytes. Three classes of gangliosides, GM1, GM4, and GD3, were also demonstrated on oligodendrocytes, while GM1 and GM4 gangliosides were detected on the surface of astrocytes. The presence of "transitional" or "bipotential" glial cells that were derived from oligodendrocytes and that expressed both oligodendroglial and astrocytic phenotypes was demonstrated. Treatment of the cells by cyclic AMP and its derivatives reversed this dual phenotypic expression back to the oligodendroglial trait. Electron microscopic examination of oligodendrocytes indicated that they were capable of synthesizing and assembling myelin sheaths in culture in the absence of any neuronal signal input.

Protein oxidation and myelinolysis occur in brain following rapid correction of hyponatremia

Myelinolysis occurs following rapid correction of hyponatremia in both humans and experimental animals. Although the mechanism of this effect at present is unknown, we have examined the possibility that a rapid rise in serum sodium following hyponatremia potentiates an oxidative stress and results in the oxidation of cellular proteins. In these studies, rats treated with 1 M NaCl following 3 days of vasopressin-induced hyponatremia exhibited myelinolysis in the corpus striatum and thalamus as well as significant increases in soluble oxidized proteins in the brain. These changes did not occur in rats treated with 0.155 M (0.9%) NaCl following 3 days of hyponatremia.

Changes in glial cell markers in recent and old demyelinated lesions in central pontine myelinolysis

An immunohistochemical study was performed to compare glial reactions in recent and old lesions of central pontine myelinolysis (CPM). Regions of demyelination and destruction of oligodendrocytes, showed reduced immunoreactivity of myelin basic protein (MBP), myelin-associated glycoprotein (MAG), transferrin, and carbonic anhydrase C (CA C). In addition, labeling of glial fibrillary acidic protein (GFAP) and S-100 protein revealed distinct dystrophic alterations of the astroglia. Remarkably, immunolabeling of GFAP was drastically reduced in astrocytic cytoplasm within freshly demyelinated lesions. Immunostaining of vimentin revealed a differential intracytoplasmic decoration of hypertrophic and dystrophic astrocytes in recent and old CPM lesions. Immunolabeling of desmin failed to stain glial cells. Monoclonal antibodies against HNK-1 exhibited greatly increased immunoreactivity both of persisting oligodendrocytes and of reactive fibrillary astrocytes in old CPM foci. In freshly demyelinated lesions, enhanced immunoreactivity of the X-hapten (3-fucosyl-N-acetyllactosamine) was prominent in astroglia and oligodendrocytes. Simultaneously, reactive astrocytes revealed intracytoplasmic labeling of laminin. Quantitation of GFAP+ astroglia in fresh CPM and control cases revealed an increase in the number of astrocytes within the demyelinated foci and in the surrounding non-demyelinated pontine tissue of CPM cases. The occurrence of astroglial alterations in the demyelinated foci of CPM could be interpreted as "astroglial dystrophy" which may represent a pathogenic factor in CPM. Furthermore, it is possible that changes of the glial microenvironment may influence the astroglia to revert transiently back to an immature phenotype as indicated by the enhanced expression of the X-hapten and HNK-1, and the de novo synthesis of vimentin and laminin.

Prominent white matter lesions develop in Mongolian gerbils treated with 100% normobaric oxygen after global brain ischemia

Carotid arteries were occluded bilaterally for 15 min in two groups of Mongolian gerbils. The first group received 100% oxygen during the first 3 h of reperfusion. During that period, room air was given to the second group. After 3 h, both groups received room air. Brains of gerbils that died within 14 days after occlusion were removed, fixed in formalin and embedded in paraffin. Gerbils that survived 15-28 days were perfused with formalin before their brains were removed and embedded in paraffin. Adjacent, serially cut sections were stained with luxol fast blue (LFB)-H&E, cresyl violet, according to the Bodian method, or immunocytochemically with antisera raised against myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP). In brain sections of gerbils receiving 3 h of 100% oxygen, there were circumscribed white matter lesions in the corpus striatum, lateral thalamus, mesencephalon and posterior limb of the internal capsule. Myelin sheaths were swollen, fragmented and were less intensely stained by MBP antiserum. MBP and LFB-stained myelin fragments were present extracellularly and in macrophages. Many axons in these areas appeared undamaged. Previously described ischemic changes were found in gray matter and some areas of white matter in both groups. However, neurons in the deeper laminae of the cerebral cortex appeared to be better preserved in gerbils given oxygen. The results suggest that hyperoxia, if present immediately after transient brain ischemia, may damage myelin more severely than other cellular elements.

Ganglioglial differentiation in medulloblastoma

A case of cerebellar medulloblastoma with clusters of mature ganglion cells and glial cells is described. The patient, a 15-year-old girl, underwent three operations followed each time by radiation and chemotherapy during the four-year clinical course. Histologically, the ganglion cells were clearly identifiable by their abundant eosinophilic cytoplasm, round nuclei with prominent nucleoli, tigroid granules, and argyrophilic fibrils and axons. Immunohistochemically, the cells were NSE- and NF-positive, and ultrastructurally they contained abundant tubules and filaments, neurosecretory granules and well developed rough endoplasmic reticulum. There were many cells transitional in appearance between primitive cells and mature ganglion cells. The tumor also had many mature yet atypical astrocytes and oligodendrocytes. The exact mechanism of the extensive neuronal and glial maturation of medulloblastoma cells is unclear, but the repetitive surgical interventions, radiation and chemotherapy might have had certain cytostatic effects on rapidly dividing medulloblastoma cells, giving them a chance to mature into postmitotic cells with potential for neuronal and glial differentiation.

Human immunodeficiency virus type 1 in spinal cords of acquired immunodeficiency syndrome patients with myelopathy: expression and replication in macrophages

Spinal cord disease is common in patients infected with human immunodeficiency virus type 1 (HIV-1), and a characteristic vacuolar myelopathy is present at autopsy in approximately one-fourth of acquired immunodeficiency syndrome patients. Pathologic examination of the spinal cord shows vacuolation of white matter and infiltration by macrophages, a process distinct from HIV-1 encephalopathy. To determine the presence and localization of HIV-1 RNA in the spinal cords of acquired immunodeficiency syndrome patients with vacuolar myelopathy, we used the technique of combined in situ hybridization and immunohistochemical staining on the same slide. Spinal cord tissue sections were stained with markers for macrophages, endothelial cells, oligodendroglia, astrocytes, and myelin and then hybridized in situ with HIV-1-specific RNA probes. Combined in situ hybridization and immunohistochemical staining on three spinal cords showed HIV-1 expression in mononuclear and multinucleated macrophages localized mainly to areas of myelopathy in spinal cord white matter. Immunohistochemical staining and electron microscopy showed myelin within macrophages and electron microscopy revealed HIV-1 budding from macrophages. These data suggest a role for HIV-1-infected macrophages locally in the pathogenesis of vacuolar myelopathy and add to the body of evidence that these cells play a role systemically in the development of HIV-1-related disease.

Are intestinal endocrine cells affected in Hirschsprung's disease? An immunohistochemical study with anti-Leu 7 monoclonal antibody

Specimens from 15 cases of Hirschsprung's disease and 22 control cases of normal guts were studied by the peroxidase-antiperoxidase (PAP) method with with anti-Leu 7 (Leu 7) monoclonal antibody (MAb). In the normal human gut, some satellite cells in the enteric plexuses and a few nerve fibers and ganglion cells in the intestinal wall were stained with Leu 7 MAb, while endocrine cells in the intestinal mucosa showed consistent and intense cytoplasmic Leu 7 positivity. In Hirschsprung's disease, the number of Leu 7-positive endocrine cells was significantly low. The mean value of the number of Leu 7-positive endocrine cells per one microscopic field (X300 magnification) was 4.6 +/- 0.6 (+/- SE) in controls and 0.7 +/- 0.3 (+/- SE) in Hirschsprung's disease (P less than .001 by Student's t test). Our findings suggest that the development of endocrine cells in the intestinal mucosa may be closely related to the development of ganglion cells in the enteric plexuses, and that the anti-Leu 7 MAb may be useful for the diagnosis of Hirschsprung's disease when biopsy specimens are limited to the mucosa only.

Myelin basic protein as a possible marker for oligodendroglioma

To search for a marker for oligodendroglioma, immunohistochemical analysis of myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) were performed on tissues from 38 oligodendrogliomas. MBP was detected in 14 such tumors, positive cells being characterized by having rather rich cytoplasm containing a large nucleus and a prominent nucleolus. They seemed to be relatively poorly differentiated cells corresponding to oligodendroglioma grade II in the WHO classification, and appeared to have some cytological resemblance to immature oligodendrocytes in the newborn brain. Mature grade I tumor cells with a small dark nucleus and a perinuclear halo, and grade III anaplastic cells were MBP-negative. GFAP-positive cells were also found in tumors containing MBP-positive cells. A double immunostain for MBP and GFAP demonstrated that some tumor cells were simultaneously stained with both. Presumably the oligodendroglioma cells that showed such dual immunostaining would intrinsically express a myelin-forming glial phenotype. MBP may be applicable as a marker for oligodendrogliomas.

Monoclonal antibody 14E identifies the oligodendrocyte cell body in normal adult human and rat white matter

A monoclonal antibody, 14E, which detects immunocytochemically the perikarya of interfascicular oligodendrocytes in sections of normal adult human and rat white matter, was obtained using isolated normal human oligodendrocytes as the immunogen. 14E is an IgM antibody that reacts with a polypeptide of approximate molecular weight 23,000 on immunoblots of the particulate fraction of normal white matter. In sections of active multiple sclerosis plaques and recent infarcts, 14E immunostained the cell bodies and processes of only a small number of hypertrophic glial cells which could be oligodendrocytes undergoing pathological changes or a subpopulation of reactive astrocytes.

Production and characterization of monoclonal antibodies against myelin-associated glycoprotein

Monoclonal antibodies against myelin-associated glycoprotein were generated by fusing mouse myeloma cells with spleen lymphocytes from BALB/c mice immunized with human myelin-associated glycoprotein purified from CNS myelin. Three groups of antibodies were identified: IgG antibodies recognizing the polypeptide moiety and IgG and IgM antibodies recognizing the carbohydrate moiety of the intact molecule. Properties of these antibodies were examined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the immunostaining technique using human CNS and peripheral nerve myelin, and ganglioside fractions isolated from human brain and peripheral nerve, and with immunohistochemical staining of human peripheral nerves. Part of human peripheral blood mononuclear cells was stained with the antibodies against the carbohydrate moiety, but not with IgG antibodies recognizing the polypeptide moiety. Natural killer activity was partially reduced after treatment of human peripheral blood lymphocytes with an IgM antibody and complement in vitro. The possibility that anti-myelin-associated glycoprotein antibodies might play a role in the pathogenesis of demyelinating diseases through modification of natural killer activity is discussed.

Gliogenesis in organotypic tissue culture of the spinal cord of the embryonic mouse. I. Immunocytochemical and ultrastructural studies

The technique of organotypic tissue culture offers an opportunity to observe in vitro complex interactions among glial cells and neurons, leading to the formation of myelin. In the present and accompanying work a combined ultrastructural, immunocytochemical and autoradiographic approach was used in a detailed study of the process of gliogenesis. Using immunocytochemical and ultrastructural criteria, differentiation along the oligodendroglia cell line is seen to be initiated a few days later than along the astroglial line. The sequence and timing of oligodendroglial differentiation both ultrastructurally and chemically follow those described in vivo. Formation of myelin has been demonstrated only by oligodendrocytes in which there is continuity between the perikaryal plasmalemma and myelin membranes. Oligodendroglial maturation culminated with the formation of light, medium and dark oligodendrocytes. The periodic acid Schiff-positive, glial fibrillary acidic protein (GFAP)-negative process of radial glial cells at explantation become GFAP-positive within 3 days, as described in vivo. Many of the astrocytes appear to have been derived from radial glial cells. Large numbers of dark glial cells, similar to the so-called 'intermediate glial cells', were seen. These were found to be astrocytes whose appearance probably reflected reaction to explantation-induced injury.

JC papovavirus large tumor (T)-antigen expression in brain tissue of acquired immune deficiency syndrome (AIDS) and non-AIDS patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a JC papovavirus infection of the central nervous system in immunocompromised patients. It is well established that demyelination in PML is caused by JC virus infection of oligodendroglia, but whether the nonstructural regulatory protein, large tumor (T) antigen, is detectable in infected human tissue was not known. Using a modification of the peroxidase-antiperoxidase technique, we found T antigen expressed in the nuclei of cells in virus-infected sites in five cases of PML studied, including two with acquired immune deficiency syndrome (AIDS). PML occurs in AIDS at a much higher frequency than in other immunosuppressive disorders, and PML in AIDS may represent a more severe form of JC virus infection of the central nervous system.

Thymosin beta 4 is a shared antigen between lymphoid cells and oligodendrocytes of normal human brain

In the normal human brain, immunoreactive thymosin beta 4, a well-characterized thymic extract, was demonstrated specifically in the cell bodies and processes of a subset of interfascicular and satellite oligodendrocytes with their stained processes terminating around myelin sheaths. Antisera directed against two other thymic polypeptides, thymosin alpha 1 and alpha 7, did not react. In lymphoid tissues, thymosin beta 4 was present in macrophages, Langerhans' cells of the skin, and the interdigitating cells of the thymus. Thus, a subset of oligodendrocytes shares a common antigen of thymic origin with the reticular-dendritic and phagocytic lymphoid cells--all Ia+ immunocompetent cells that participate in the presentation of antigens to T cells. The subset of thymosin beta 4-positive oligodendrocytes is antigenically distinct and may play a role in the immune surveillance of the central nervous system or the demyelinating processes induced by antigen-presenting activated macrophages.

Immunohistochemical characterization of oligodendrogliomas: an analysis of multiple markers

Twenty-eight oligodendrogliomas and seven oligoastrocytomas were immunotested by the peroxidase-antiperoxidase (PAP) method with antiglial fibrillary acidic protein (GFAP) serum, anti-Leu 7 monoclonal antibody (Mab), anti-myelin-associated glycoprotein (MAG) Mab, anti-myelin basic protein (MBP) serum, anti-carbonic anhydrase C (CA C) serum and anti-neuron-specific enolase (NSE) serum. The immunoreactivity of their vascular pattern was studied with Ulex europaeus type I lectin (UEA I). According to their morphology and distribution GFAP-positive cells were respectively interpreted as reactive astrocytes, neoplastic astrocytes and neoplastic oligodendrocytes. Reactive astrocytes were found in the tumor, around the tumor and surrounding the supporting blood vessels. Neoplastic astrocytes were mainly found in the oligoastrocytomas and usually closely intermingled with neoplastic oligodendrocytes. GFAP-positive neoplastic oligodendrocytes were found in the typical oligodendrogliomatous areas. They had central nuclei and GFA positivity was mainly found in the perinuclear cytoplasm. They correspond to the "gliofibrillary oligodendrocytes" described by Herpers and Budka. Of the oligodendrogliomas 91% displayed Leu 7 positivity, but anti-Leu 7 cannot be considered as a specific marker for oligodendrogliomas since other neuroepithelial tumors have been reported to react with this antibody. MAG-, CA C- and NSE-positivities were found in a number of tumor cells in a few oligodendrogliomas. All the tumor cells were MBP-negative, but myelin sheaths and fragments of myelin in the infiltrated white matter were clearly demonstrated by this antiserum. UEA I strikingly demonstrated the vascular pattern of the tumors, and its usefulness as a discriminating marker for the supportive endothelial cells was confirmed.

Human natural killer cell activity is reduced by treatment of anti-myelin-associated glycoprotein (MAG) monoclonal mouse IgM antibody and complement

Human mononuclear cells could be stained by anti-myelin-associated glycoprotein (MAG) monoclonal mouse IgM antibody. The remaining human natural killer (NK) cell activity examined by using K-562 cells at 20:1 as effector:target ratio after treatment of anti-MAG monoclonal mouse or anti-Leu-7 (HNK-1) antibody and complement revealed 13.4% and 15.1%, respectively (untreated NK activity was 40.8%). However, human NK activity could be abrogated by anti-Leu-11 and complement. The remaining NK activity shown as lytic units after treatment with anti-MAG, anti-Leu-7 or anti-Leu-11 and complement was 6.1, 5.3 and below 1.0, respectively (untreated NK cells showed 15.4). When NK activity was examined in another target cell, MOLT-4, the remaining activity shown as lytic units was also decreased with anti-MAG antibody (4.3) or with anti-Leu-7 (3.0) (untreated NK activity was 8.3). Our findings suggest that NK cells may be influenced by anti-MAG antibody if it is found in the sera as anti-lymphocytotoxic antibody.

A quantitation of myelin-associated glycoprotein and myelin basic protein loss in different demyelinating diseases

The loss of myelin-associated glycoprotein (MAG) and myelin basic protein (MBP) was compared by quantitative immunocytochemistry in demyelinating lesions of measles encephalomyelitis (ME), multiple sclerosis (MS), and progressive multifocal leukoencephalopathy (PML). Serial sections from paraffin-embedded tissue were reacted with antisera for MAG and MBP, and areas of staining loss were compared morphometrically. Lesions in ME showed MAG loss equal to that of MBP, lesions of PML showed MAG loss greater than that of MBP, and MS lesions showed a mixture of patterns. These data demonstrate distinctive patterns of MAG and MBP loss in these three diseases.

Spinal cord multiple sclerosis lesions in Japanese patients: Schwann cell remyelination occurs in areas that lack glial fibrillary acidic protein (GFAP)

To extend earlier observations on Schwann cell remyelination in multiple sclerosis (MS) lesions (Itoyama et al. 1983) we immunostained spinal cord sections from eight Japanese MS patients with antiserum to Po glycoprotein, a major constituent of peripheral nervous system (PNS) myelin, myelin basic protein (MBP), and glial fibrillary acidic protein (GFAP). Spinal cord sections from six of the eight Japanese MS patients contained large clusters of peripheral myelin sheaths with anti-Po immunoreactivity. In lesions found in four of the six patients, thousands of Po-stained PNS myelin sheaths were present. Necrosis was prominent in these lesions which included more than half of the spinal cord's transverse area. The number and density of regenerating myelin sheaths of peripheral origin were much greater than we observed in MS spinal cord lesions of white people (Itoyama et al. 1983). Anti-GFAP immunoreactivity was present in most brain and spinal cord lesions. However, the areas in lesions that contained large groups of PNS myelin sheaths lacked anti-GFAP immunoreactivity. Our data suggest that spinal MS lesions that are large, severely demyelinated, and partially necrotic may contain factors that inhibit fibrous astrogliosis. These factors, other substances in the large lesions and/or the lack of astrocytic scarring could then promote Schwann cell invasion, multiplication, and remyelination of surviving axons.

Immunohistochemistry of soft tissue tumours: a review

The diagnosis and classification of soft tissue sarcomas can pose difficult problems for the histopathologist. Many sarcomas are too poorly differentiated to exhibit morphological features specific enough to define their histogenesis. Using the immunoperoxidase technique with commercially available antisera as a routine adjunct to other diagnostic aids, it is possible to arrive at more accurate diagnoses on which treatment protocols can be based. In addition a better understanding of mesenchymal neoplasms and their origins can be obtained by functional immunohistochemical studies.

Atypical multiple sclerosis with concentric or lamellar demyelinated lesions: two Japanese patients studied post mortem

In two Japanese patients with atypical multiple sclerosis studied post mortem, there was a concentric or lamellar pattern of demyelinated lesions. This was detected in the thoracic spinal cord of one patient and in the optic chiasm of the other. In addition, lesions more typical of multiple sclerosis were present. Clinically, both cases ran courses intermediate between Baló's disease and multiple sclerosis. The patients had a relatively rapid progression of disease and had severe visual disability or paraplegia associated with fever, headache, and pleocytosis. The formation of a concentric or lamellar pattern of the lesions in cases of demyelinating diseases may relate to the brief duration or to the acuteness or severity of the disease process.

Immunocytochemical study of myelin-associated glycoprotein (MAG), basic protein (BP), and glial fibrillary acidic protein (GFAP) in chronic relapsing experimental allergic encephalomyelitis (EAE)

Chronic relapsing experimental allergic encephalomyelitis (EAE) lesions that resemble those seen in multiple sclerosis (MS) were produced in young Hartley and strain 13 guinea pigs (Lassmann and Wisniewski 1979). To study distributions of myelin-associated glycoprotein (MAG), myelin basic protein (MBP), and glial fibrillary acidic protein (GFAP) in these lesions, paraffin and semithin epon sections of CNS from eight of these guinea pigs were immuno-stained with antisera to these proteins according to the peroxidase-antiperoxidase (PAP) method. In lesions with active myelin sheath breakdown, changes in anti-MAG and anti-BP immunoreactivity corresponded closely. Abnormal and/or decreased anti-MAG staining did not extend beyond margins of lesions into surrounding areas containing myelin sheaths stained normally by anti-BP and by histological stains for myelin. GFAP-stained astrocyte processes were more numerous and much larger in more chronic lesions. Anti-MAG and anti-BP both stained regenerating myelin sheaths which were very numerous in both paraffin and epon sections. In the latter, anti-MAG also stained some myelin-forming oligodendroglia. The results are additional evidence suggesting that in chronic relapsing EAE, myelin sheaths are the primary target. Oligodendroglia appear to be relatively unaffected and remyelinate most of the demyelinated axons.

Immunocytochemical localization of herpes simplex virus antigen in the trigeminal ganglia of experimentally infected mice

The peroxidase anti-peroxidase (PAP) technique was used to study the distribution of herpes simplex virus (HSV) antigens in mouse ganglia during the acute infection and the transition into the latent infection. At 2 days after HSV inoculation by the corneal route, immunoperoxidase staining was present in occasional isolated neurons of the trigeminal ganglion and also in scattered satellite cells. By 4 days, more cells were stained with the infection centered in the medial portion of the ganglion. Inflammatory cells were present around PAP-labeled fragments from lysed cells. Stained satellite cells often with a hypertrophic appearance surrounded labeled or unlabeled neurons in a ring-like array. At 6 days after HSV inoculation, there was a decrease both in the number of cells stained and in the intensity of staining. By 8 days, HSV antigens could be detected by weak PAP staining only in neurons. Otherwise, these neurons appeared morphologically normal. No immunoperoxidase staining was present after the 8th day. These results are compatible with retrograde axoplasmic transport of HSV and cell to cell spread of virus in ganglia. Also the appearance of infected ganglion cells during the transition to latency suggests that neurons can be switched from an HSV-permissive to a non-permissive (latent) state.

Necessity of continuous antigenic stimulation by the locally retained antigens in chronic relapsing experimental allergic encephalomyelitis

Chronic relapsing experimental allergic encephalomyelitis has been induced in juvenile strain 13 guinea pigs with isologous spinal cord in Freund's complete adjuvant. Retention of antigen at the injection site and in the draining lymph nodes was studied by immunocytochemical staining with antiserum to myelin basic protein (BP). Antigen was detected in the skin more than 370 days after immunization, whereas it could be detected in the nodes only 200 days postinjection. Amputation of the hind feet to remove the antigenic depots prevented subsequent episodes of clinical EAE. Therefore, continuous antigenic stimulation by the antigen at the local skin site is more important in the induction of relapses than antigen in the draining lymph nodes.

Immunohistochemistry of central nervous system tumors. Its contributions to neurosurgical diagnosis

Immunofluorescence and immunoperoxidase (peroxidase-antiperoxidase, PAP) techniques for the demonstration of neural and non-neural cell markers are contributing greatly to increase the diagnostic accuracy of difficult tumors of the central nervous system. Well characterized nervous system markers include glial fibrillary acidic (GFA) protein, the three protein subunits of neurofilaments, neuron-specific enolase (NSE), myelin basic protein, and S-100 protein. The most important and reliable of these is GFA protein, which is widely in use for the immunohistochemical diagnosis of tumors of the glioma group. Its many practical applications are reviewed and illustrated. Other neural markers, in particular the specificity of NSE and S-100 protein, need to be critically evaluated. Problems related to the immunohistochemical diagnosis of central neuroepithelial tumors of putative neuroblastic origin remain complex and still need to be resolved. Non-neural markers, such as vimentin, desmin, cytokeratins, Factor VIII, alpha-fetoprotein, human chorionic gonadotropin, and immunoglobulins have well defined, although more restricted, applications in surgical neuropathology.

Measles encephalomyelitis: lack of evidence of viral invasion of the central nervous system and quantitative study of the nature of demyelination

Measles encephalomyelitis appears to be an immune-mediated parainfectious disorder, but it is unclear whether viral invasion of brain is an obligate step in its development. Immunocytochemical methods were used to search for virus antigen in formalin-fixed, paraffin-embedded central nervous system (CNS) tissues from 10 patients with measles encephalomyelitis and 12 patients who had died of measles without CNS involvement. All the CNS tissues studied were viral antigen negative. Similarly fixed CNS tissues from all of 6 patients with subacute sclerosing panencephalitis were viral antigen positive and served as controls. The pattern of perivenular demyelination was also determined in 4 cases of measles encephalomyelitis using antibodies to myelin associated glycoprotein and myelin basic protein and a Luxol fast blue stain. Areas of demyelination in serial sections were quantitated, and no morphometrical differences were found among tissues stained with the three stains. The data suggest the lack of virus replication in the CNS during encephalomyelitis or fatal measles without CNS symptoms. The pattern of loss of myelin associated glycoprotein and myelin basic protein in regions of perivenular demyelination resembles that reported in experimental allergic encephalomyelitis. This pattern of demyelination has been proposed to result from a primary attack on the myelin sheath rather than from direct involvement of the oligodendroglial cell.

The function of perineuronal satellite oligodendrocytes: an immunohistochemical study

Perineuronal satellite oligodendrocytes in the mouse have been investigated immunocytochemically using antisera to myelin basic protein and myelin-associated glycoprotein. In the normal animal, during remyelination, and following trauma the staining characteristics of these cells resembled those of other grey and white matter oligodendrocytes. It is concluded that these cells are, in many respects, functionally similar to other oligodendrocytes.

Myelin-associated glycoprotein (MAG) distribution in human central nervous tissue studied immunocytochemically with monoclonal antibody

Recent biochemical data show that myelin-associated glycoprotein (MAG) is the antigen for a monoclonal antibody found in sera of patients with IgM paraproteinemia and neuropathy (Braun et al. 1982). Immunoreactivity of this antibody with CNS has not been described. To study this, monoclonal anti-MAG was used in the avidin-biotin-peroxidase complex method (Hsu et al. 1981) to immunostain paraffin and epon sections of human CNS. Well characterized polyclonal MAG antiserum (Quarles et al. 1981) was employed in comparison tests. In paraffin sections of developing CNS, both monoclonal and polyclonal MAG antisera stained oligodendroglia and myelin. In adult CNS, periaxonal regions of myelin sheaths were immunostained in paraffin sections and semithin epon sections treated with monoclonal and polyclonal anti-MAG. In electron-microscopic experiments that included milder pretreatment of epon thin sections and more precise reaction product localization, entire thickness of myelin sheaths were immunostained. Thus, in electron micrographs, monoclonal and polyclonal anti-MAG immunoreactivity also have the same localization. In other electron-microscopic experiments, the same reaction product localization was observed with antiserum to myelin basic protein (MBP), a known constituent of compact myelin. Thus, results with this monoclonal anti-MAG provide important new evidence to support the localization of MAG in compact CNS myelin. Our data also suggest that monoclonal antibodies against MAG will be useful in studies of the pathogenesis of multiple sclerosis and other demyelinating diseases.

Developmental changes of glial fibrillary acidic protein and myelin basic protein in perinatal leukomalacia: relationship to a predisposing factor

Focal white matter necrosis is frequently seen in the brains of infants with perinatal cerebral hypoperfusion. Periventricular leukomalacia (PL) occurs in the deep white matter of premature and term neonates and subcortical leukomalacia (SL) in the subcortical white matter of young infants. Using immunoperoxidase methods in normal infants, glia positive for glial fibrillary acidic protein (GFAP) were found first in the deep zones of white matter and with increasing age they became more prominent in the subcortical zone. They increased diffusely in the deep or subcortical zones of the cases of PL or SL, respectively. The number of myelin basic protein-positive glia is much larger than that of GFAP-positive glia in the cases of old PL. These findings suggest that an increased number of positive glia may be a reaction to hypoxic, ischemic, or toxic insults, or this shifting, transient increase of positive glia in cerebral white matter may be one of several predisposing factors leading to perinatal leukomalacia. Furthermore, positive staining of GFAP and MBP for reactive astrocytes in old PL suggests that at a certain stage of gliogenesis both GFAP and myelin basic protein may be present within the same cell.

An immunohistochemical study of myelin proteins during remyelination in the central nervous system

The process of remyelination in the superior cerebellar peduncles of mice following demyelination with Cuprizone was studied immunohistochemically using antisera to myelin basic protein (MBP) and myelin-associated glycoprotein (MAG). Demyelination occurred after formation of myelinic vacuoles and resulted in almost complete loss of demonstrable MBP and MAG from the peduncle. Prior to the onset of remyelination, oligodendrocytes with cytoplasmic staining for both proteins appeared in the peduncle. These cells were then associated with remyelinating axons. The axons were remyelinated in clusters until the MBP and the MAG in the whole peduncle were reconstituted, although the axon sheaths were thinner than those in normal animals. The results show that the immunohistochemical distribution of MBP and MAG in remyelinating axons resembles that in normal axons, and that the expression of myelin proteins in oligodendrocytes during remyelination reverts to that seen during normal development.

Immunohistological demonstration of serum proteins and structural and viral antigens in paraffin sections of nervous tissues

A brief outline is given of applications of immunohistological techniques to the study of normal and diseased nervous tissue. Protease treatment of paraffin sections usually enhances sensitivity and reliability both of IF and PAP techniques. Sensitivity of immunohistological examination of paraffin sections is comparable to that of virus detection by normal virological techniques in animal rabies and slightly superior to EM search for virions in SSPE and PML. Immunostaining for MBP appears to be the most sensitive method for myelin, especially for demonstration of very thin myelin sheaths, which are important in studies of myelogenesis and cortical myeloarchitecture. Prolonged fixation in formalin clearly diminishes or abolishes immunoreactivity. Compacted myelin stains less well for MBP than preparative myelin artefacts and the surface of myelinated fibers. GFAP production is enhanced when glioma cells invade surrounding mesenchymal structures. The chance finding of GFAP-like immunoreactivity in a cancer metastasis casts doubt on the astroglial specificity of GFAP.

Myelin-associated glycoprotein: electron microscopic immunocytochemical localization in compact developing and adult central nervous system myelin

Light microscopic immunocytochemical studies have shown that myelin-associated glycoprotein (MAG) is localized in myelin of the developing CNS; but in the adult, MAG appears to be restricted to periaxonal regions of myelinated fibers. To extend these observations, we embedded optic nerves of 15-day-old rats, adult rats, and an adult human in epon after aldehyde and osmium tetroxide fixation. After 5% H2O2 pretreatment, thin sections were immunostained with 1:250-1:5,000 rabbit antiserum to rat CNS MAG according to the avidin-biotin-peroxidase complex (ABC) method. Dense deposits of reaction product covered compact myelin in both developing and adult optic nerves. When we used 1:500, 1:1,000, and 1:2,000 anti-MAG, less intense immunostaining of myelin was found. We also obtained the same localization in compact myelin with the peroxidase-antiperoxidase (PAP) method. With 1:250 anti-MAG, dense deposits of reaction product were not observed on axolemmal membranes or on oligodendroglial membranes located periaxonally and paranodally. In thin sections of adult human optic nerve, anti-MAG also stained compact myelin intensely. When thin sections of rat and human optic nerves were treated with preimmune or absorbed serum, no immunostaining was observed. Immunoblot tests showed that our MAG antisera did not react with any non-MAG myelin proteins. In contrast with earlier light microscopic data, this study shows that MAG localization does not change during CNS development; both developing and adult compact myelin sheaths contain MAG. As many biochemical studies also show that MAG is present in compact myelin, we suggest that this 100,000 dalton glycoprotein now be called myelin glycoprotein (MGP) instead of MAG.

Abnormal cell relationships in Jimpy mice: electron microscopic and immunocytochemical findings

The mutant mouse strain Jimpy is characterized by a deficiency of myelin formation throughout the C.N.S. The cause of this hypomyelination is unknown. Based on previous reports, astrocytes, axons and oligodendrocytes are all altered, but no single cell type can be unequivocally defined as the primary target. Jimpy and age-matched normal mice were investigated using thin sectioning, freeze-fracturing and immunocytochemistry. We examined optic nerves and cervical spinal cords of Jimpy to determine which cells were morphologically altered during the period which precedes the onset of myelination and which cellular alterations persisted during myelinogenesis. Abnormalities of astrocytes and axons were frequently observed in Jimpy not only during myelination but also in early postnatal development before mature oligodendrocytes were present. The early astrocytic changes included hyperplasia and alterations of both cytoplasm and plasma membrane. An unusually complex network of astrocytic processes divided the axons into very small groups. During myelination, astrocytic processes were found insinuated between the axons and myelin sheath and/or within the myelin lamellae. Immunocytochemical investigations also revealed a complex network of glial fibrillary acidic protein-positive processes in contact with the majority of the axons. At stages prior to myelination axonal alterations were detected. Most of the axons were not in close contact with one another and individual axons had an undulating and irregular course. In areas where axon separation by astrocytic processes occurred, axonal diameters were more variable than the homogeneously sized axons of the normal mice. Our immunocytochemical results at stages during myelination showed not only many myelin basic protein-positive processes around axons in Jimpy but also clearly immunostained myelin sheaths. This indicates that the myelinating glia present not only produce myelin basic protein but can also incorporate it into the myelin spiral. The presented results suggest that the mouse mutant Jimpy could be a model for disturbed cell interactions in the C.N.S. Therefore, the hypomyelination may not be attributed to a defect of a single cell but rather to a deficiency in both macroglial types and, perhaps, the axon as well.

Schwann cell remyelination of demyelinated axons in spinal cord multiple sclerosis lesions

To investigate remyelination in multiple sclerosis lesions, we immunostained spinal cord sections from patients with multiple sclerosis and neurological normal (control) patients with antisera to P0 protein, a major constituent of peripheral nervous system myelin, and myelin basic protein, which is found in both central and peripheral nervous system myelin. In sections from five of the eight patients with no clinical or pathological evidence of neurological disease, P0 immunostaining was confined to peripheral myelin sheaths in dorsal and ventral roots. They were intensely stained, and peripheral--central nervous system transition zones were clearly demarcated. Sections from the other three control patients contained a few P0-stained sheaths in the central nervous system near root entry zones or among marginal glia near the dorsal sulcus. Spinal cord sections from six of the ten patients with multiple sclerosis contained clusters of myelin sheaths immunostained by P0 antiserum. These regenerating sheaths of peripheral nervous system origin were most numerous in large lesions and were commonly located in central areas or peripherally near root entry zones. The sheaths were observed frequently in areas of active demyelination and appeared morphologically normal even when surrounded by debris-filled macrophages. Near margins of small inactive plaques were a few basic protein--stained oligodendroglia extending processes to thin basic protein--stained sheaths.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical investigations of murine leukodystrophies. A study of the mutants 'jimpy' (jp) and 'myelin deficient' (mld)

Sections of the central nervous system of the leukodystrophic mouse mutants 'jimpy' (jp) and 'myelin deficient' (mld), as well as of healthy littermates, were immunostained for glial fibrillary acidic protein (GFA), myelin basic protein (MBP) and myelin-associated glycoprotein (MAG). Adjacent sections were stained conventionally for myelin. In jp, GFA-stained astrocytes were abnormally prominent already at the age of 12 days. A considerable amount of MBP and MAG was present in the vicinity of axons, although no myelin was visible in the conventional stains for myelin. In mld, GFA-staining astrocytes were present in normal numbers. MAG could be demonstrated in its normal localization along axons, but MBP was visible only in the comparatively old animal (85 days). Here, it was demonstrated in an abnormal site--the perikarya and the proximal parts of the processes of oligodendrocytes. Thin myelin sheaths present in this animal could not be stained for MBP.

Immunohistochemical study of myelin sheaths formed by oligodendrocytes interacting with dissociated dorsal root ganglion neurons in culture

The addition of central nervous system (CNS) glial cells to dissociated networks of rat dorsal root ganglion neurons in tissue culture provided a useful system for the study of CNS myelin sheath formation. The CNS myelin basic proteins (BP) and proteolipid protein (PLP) were demonstrable in these cultures by immunoperoxidase techniques. Both BP and PLP were detectable in myelinating oligodendrocytes and CNS myelin sheaths. Anti-BP serum and anti-PLP serum were useful immunohistochemical staining reagents for the identification of myelinating oligodendrocytes and CNS myelin sheaths in tissue culture.