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Monocytes, macrophages, and brain microglia are the primary cell types most readily demonstrated to be infected in CNS lesions of patients infected with HIV (Koenig et al., 1986). Microglia are implicated in mediating CNS immune regulation and neural tissue injury associated with the AIDS-dementia syndrome. This report describes the isolation and characterization of microglia from the adult human central nervous system (CNS), and the assessment of microglial immune accessory/effector functions, some of which might be altered in CNS infectious and autoimmune diseases. In our studies we have compared the in vitro properties of microglia with peripheral blood monocytes/macrophages, and with astrocytes, a CNS cell type also implicated in contributing to immune regulatory and effector functions. Additionally, we have compared phenotypic features of resident microglia in situ with monocytes and macrophages that have infiltrated the CNS during the course of CNS inflammation. Our results suggest that adult human derived parenchymal microglia represent a unique cell of monocytic origin that can be distinguished both in vitro and in situ from monocytes/macrophages recently infiltrating into the CNS and from perivascular macrophages/microglial cells. Our data demonstrate that parenchymal microglia express several immune accessory/adhesion molecules that can provide second signals for CD4+T cell stimulation. Furthermore, microglia can synthesize cytokines and reactive oxygen species that may augment ongoing pathology in the CNS of AIDS patients. Infection of resident brain microglia could augment microglial immune accessory/effector functions possibly contributing to pathology seen in HIV dementia.

Cytokine production by T cells in the cerebrospinal fluid (CSF) and central nervous system (CNS) of SJL/J mice during myelin basic protein (MBP)-induced experimental allergic encephalomyelitis (EAE) was examined. Reverse transcriptase/polymerase chain reaction (RT/PCR) was used to measure interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) mRNA levels from perfused CNS tissue (brain and spinal cord) and from cells isolated from CSF. Animals were grouped according to EAE severity, ranging from asymptomatic (adjuvant only) to severe disease (paralysis or severe paresis). Cytokine signals, normalized to actin, were almost undetectable in control tissues, and only slightly elevated in whole CNS tissue from animals with mild EAE. Both cytokine messages were strongly upregulated in CNS tissues derived from severely affected animals, consistent with previous observations correlating disease progression with infiltration by memory/effector CD4+ T cells, the major source of these cytokines. This cytokine upregulation was specific to the CNS, since other organs from the same animals did not express significant levels of IL-2 and IFN-gamma. CSF was obtained from the cisterna magna of unperfused mice and verified as such by absence of red blood cells (RBCs) and by immunoglobulin concentration orders of magnitude lower than in serum. Cytokine message was measured in RNA isolated from cells in CSF. Levels of IL-2 and IFN-gamma mRNA in CSF cells were significantly elevated in mild EAE and strongly upregulated in severe disease, correlating with those in total CNS tissue. These results confirm the CSF as representative of the immune status of the CNS and indicate a role for IL-2 and IFN-gamma in inflammatory CNS disease.

We are investigating the potential of in vivo proton magnetic resonance spectroscopy for noninvasive characterization of the chemical pathology of plaques in magnetic resonance brain images from patients with multiple sclerosis. Spectra localized to chronic, irreversible plaques showed a decrease in the ratio of N-acetyl/creatine resonance intensities relative to normal-appearing white matter. Spectra localized to active plaques showed different metabolite changes as compared with spectra from identical, plaque-free volumes in the contralateral hemispheres. Some active plaques showed either no abnormalities or only an increase in tissue lactate. Spectra from others showed an increased ratio of choline/creatine resonance intensities, with or without a decreased N-acetyl/creatine resonance intensity ratio. In one case, serial observations showed an evolution of changes in spectra from a single plaque from an increased choline/creatine ratio to a decreased N-acetyl/creatine ratio. These observations suggest that proton magnetic resonance spectroscopy may be able to distinguish acute or active from chronic plaques and to characterize the pathologic evolution of active plaques by measurement of local tissue metabolite levels.

Image localized, water-suppressed proton magnetic resonance spectra were obtained from affected brain in patients with multiple sclerosis. In patients with moderate to severe chronic disease, spectra revealed a decreased ratio of N-acetylaspartate to creatine resonance intensities. A normal ratio was obtained from a large recently symptomatic MRI plaque that resolved without sequelae. We propose that the observed metabolite changes can be useful as an index of irreversible CNS injury.

Didemnin B, a highly active depsipeptide isolated from a Caribbean tunicate, crystallizes from chloroform/benzene in the orthorhombic space group C2221, with cell parameters a = 14.990 +/- 0.003 A, b = 22.574 +/- 0.004 A, c = 41.112 +/- 0.009 A, V = 13911.7 A3 at 138 K and a calculated density of 1.143 g/cm3 based on C57H89N7O15, 1.5C6H6.H2O and eight formula units per cell. The overall agreement factor R = 0.052 for 7699 reflections, 20 theta max = 150 degrees, Cu K-alpha radiation. The structure determination revealed that didemnin B contains an isostatine residue instead of a statine residue. The conformation of the 23-membered depsipeptide ring is stabilized by one transannular hydrogen bond. The ring does not show the antiparallel beta-pleated-sheet structure but, instead, has a fold in the shape of a bent figure-eight. The linear peptide moiety, containing N-methylleucine and lactylproline, forms a beta (II)-bend and is folded back toward the cyclic backbone, giving the overall molecule a globular character. Comparison with the structure of cyclosporin A shows distinct stereochemical differences between the two molecules. It is suggested that didemnin B and cyclosporin A are unlikely to have a common receptor binding site.

Activated suppressor cell function mediated by either freshly isolated peripheral blood mononuclear cells (MNCs), freshly isolated CD8+ lymphocytes or by CD8+ cell lines, has previously been found to be reduced compared to controls in multiple sclerosis (MS) patients with progressive disease (MS-P). In this study, we found that suppressor activity mediated by CD8+ cell lines, derived from MS patients with stable disease (MS-S) patients and maintained in culture for 14 days, was significantly greater (45 +/- 6%) compared to that mediated by MS-P patients' CD8+ cells (11 +/- 4%, P less than 0.005). The MS-S suppressor values were, however, suggestively reduced compared to controls (60 +/- 6%, P less than 0.05). MNC-mediated suppressor values for the MS-S group (61 +/- 5%) did not differ from the control group (67 +/- 6%). Values for the MS-P group (7 +/- 6%) were significantly reduced compared to MS-S and control groups. Cytotoxic activity mediated by CD8+ cell lines showing defective suppressor function did not differ from control values. The cell lines in MS and control did not differ with respect to their rate of proliferation in the presence of IL-2 and OKT3. Suppressor function in this assay was ablated if exogenous IL-2 was removed from the culture media. These data suggest that defective activated suppressor function is characteristic of the progressive form of MS, although a suppressor defect is also partially expressed in stable MS patients when CD8+ cell lines are studied.

Activated suppressor cell function, induced with either concanavalin A or OKT3 and mediated by either unfractionated mononuclear cells or "panning" enriched T8+ cells, freshly isolated from peripheral blood, is reduced in patients with progressive multiple sclerosis (MS) as compared with control donors. In this study, we generated T8+ cell lines from the peripheral blood of these same patients and controls. Suppressor activity, mediated by T8+ cells exposed to OKT3 on days 1, 7, and 14 of culture and then treated with mitomycin C on day 16, was significantly reduced in the MS group (mean percent suppression 13% +/- 5) as compared with the control group (68% +/- 6, n = 8, p less than 0.001). No differences were noted in [3H]thymidine uptake by the OKT3-stimulated T8+ cell lines of MS and control groups. Mean percent suppression mediated by T4+ cell lines did not differ between MS and control groups (15% +/- 4, n = 3, vs 22% +/- 2, n = 4). These current data suggest that the previously observed defect in T8+ cell-mediated activated suppressor cell function in MS is a persistent one, favoring the postulate that the defect reflects intrinsic alterations in this cell population rather than a transient effect of serum factors on T8+ cell function.

Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of the upper motor neurons in the frontal cortex and the motor neurons of the brain stem and spinal cord. Cranial nerve nuclei III, IV, VI are usually normal histopathologically, as are the eye movements clinically. Using electro-oculography, we found decreased saccadic or smooth pursuit velocities in four of ten patients unidirectional saccadic pursuit in one of these four, and progressively decreasing saccadic velocities in another. We believe the defect is supranuclear and that the ocular motor system is more often abnormal in patients with ALS than previously recognized.

Eighteen black patients with narcolepsy underwent human leukocyte antigen (HLA) typing. Eleven of the 18 had cataplexy. Twelve patients (66.6%) had HLA-DR2; 7 patients with cataplexy had DR2. All patients had DQw1. In contrast to white and Japanese patients studied to date, not all black narcoleptics have DR2.

Sensory neuropathies developed in three of four patients with prurigo nodularis who had been treated with thalidomide. The serum samples of the patients who had neuropathy produced morphologic changes in cultured dorsal root ganglion cells. These observed changes support the postulate that thalidomide induces primary neuronal degeneration.

Effects of the anti-T-cell monoclonal antibodies OKT3, OKT5, and OKT8 on T-cell surface properties and cell functions were evaluated. Incubation of mononuclear cells isolated from peripheral blood for 48 hr with each monoclonal antibody in the absence of complement resulted in modulation of their respective surface antigens; i.e., the number of cells detected by immunofluorescence as positive for the T3, T5, and T8 surface antigens was reduced. T3, T5, and T8 antigens modulated independently. A radiolabeled second antibody technique confirmed modulation by OKT3 and OKT8 and indicated that T-cell differentiation antigens can regenerate in culture. Incubation of mononuclear cells with OKT3 increased the number of sheep erythrocyte-binding lymphocytes (E+-rosetting cells) and markedly increased the number of avidly E+-rosetting cells. Incubation with OKT8 reduced the number of E+- and of avidly E+-rosetting cells. OKT3 induced both mitogenic reactivity and suppressor cell activity; cells modulated by OKT8 exhibited reduced mitogenic reactivity and reduced suppressor cell function. The decreases in total T cells, in avid T cells, in suppressor cell number, and in suppressor cell function that follow modulation by OKT8 mimic changes observed in multiple sclerosis patients.