Intra-blood-brain-barrier synthesis of HTLV-III-specific IgG in patients with neurologic symptoms associated with AIDS or AIDS-related complex

Adamantane as a brain-directed drug carrier for poorly absorbed drug. 2. AZT derivatives conjugated with the 1-adamantane moiety

Five AZT (azidothymidine) prodrugs conjugated with the 1-adamantane moiety via an ester bond were synthesized to improve the transport of AZT into the central nervous system (CNS). In in vitro degradation studies with rat and human plasma, it was demonstrated that the prodrugs were degraded enzymatically and converted quantitatively to their parent drug. AZT. As assessed by octanol-buffer partitioning, the prodrugs were much more lipophilic than AZT and were expected to penetrate the blood-brain barrier (BBB) readily. In in vivo studies, in which the prodrugs were administered intravenously to rat, the prodrugs in brain tissue were detected at 7-18 times higher concentrations than AZT in spite of the negligible amount of the prodrug in the cerebrospinal fluid. These results indicate that the introduction to AZT of the 1-adamantane moiety results in the enhancement of the BBB penetration. This pharmaceutical approach would be beneficial for the efficient treatment of the CNS infection by human immunodeficiency virus.

Human spumaretrovirus antibody reactivity in multiple sclerosis

The role of human spumaretrovirus (HSRV) infections in the pathogenesis of multiple sclerosis (MS) was investigated with recombinant HSRV env-specific enzyme-linked immunosorbent assay. The presence of HSRV antibodies was determined in pairs of serum and cerebrospinal fluid (CSF) samples from 60 MS patients. In 7 of these patients serial serum and CSF samples were obtained in relation to the clinical activity of the disease during a period of 2 years. No increased antibody reactivity was demonstrable in the MS population compared with 14 aseptic meningitis patients, 50 blood donors and 16 healthy controls. Slightly elevated levels of antibodies were demonstrable in serum and/or CSF in 4 MS patients but also in 1 patient with aseptic meningitis, 1 blood donor and 1 child. No marked serum or CSF HSRV antibody fluctuation was observed in the MS patients followed longitudinally. Thus, this study does not support the involvement of HSRV in the pathogenesis of MS.

Intrathecal synthesis of IgG in simian immunodeficiency virus (SIV)-infected rhesus macaques (Macaca mulatta)

We examined cerebrospinal fluid (CSF) and serum from 25 simian immunodeficiency (SIV)-infected rhesus macaques for the presence of SIV-specific immunoglobulin G (IgG) and for intrathecal synthesis of IgG. SIV-specific IgG was present in CSF from almost 50% of the macaques. In approximately half of these animals the SIV-specific IgG appeared to be derived from serum by leakage across a disrupted blood-brain barrier, whereas in the remaining animals there was evidence of intrathecal IgG synthesis. There were no significant associations between CSF SIV-specific IgG, intrathecal IgG synthesis and isolation of virus from CSF, clinical status, or neuropathological findings. However, SIV-specific IgG was absent from CSF in all four of the macaques with SIV encephalitis. The presence of SIV-specific IgG in CSF may have a modulating effect on the development of SIV-associated neurological disease.

The virology of demyelinating diseases

Infectious agents have been postulated as causes of multiple sclerosis for over a century. The possible role of a virus or viruses is supported by data that (1) a childhood exposure is involved and "viral" infections may precipitate exacerbations of disease, (2) experimental infections in animals and natural infections in humans can cause diseases with long incubation periods, remitting and relapsing courses, and demyelination, and (3) patients with multiple sclerosis have abnormal immune responses to viruses. The pathogenesis of three human demyelinating diseases of known viral etiology is discussed. In progressive multifocal leukoencephalopathy, a papovavirus selectively infects oligodendrocytes and causes focal areas of demyelination. In postmeasles encephalomyelitis, the virus is lymphotrophic and disrupts immune regulation that can result in an autoimmune perivenular demyelinating illness without evidence of infection of the central nervous system. In human immunodeficiency virus-encephalopathy and myelopathy virus is present in macrophages and microglia and the myelin abnormalities apparently are caused by soluble factors such as viral proteins, cytokines, or neurotoxins. These findings may have implications on how, when, and where to seek viruses in multiple sclerosis.

Low levels of specific T cell activation marker CD27 accompanied by elevated levels of markers for non-specific immune activation in the cerebrospinal fluid of patients with AIDS dementia complex

Concentrations of soluble receptors for tumor necrosis factor (sTNFR-p55 and sTNFR-p75) and soluble T cell antigens CD25 and CD27 (sCD25 and sCD27) were measured in paired serum/cerebrospinal fluid (CSF) samples of 15 patients with AIDS dementia complex (ADC) and 15 HIV-infected control subjects (11 with other central nervous system (CNS) infections and four without CNS infection). In this study levels of sTNFR-p55, sTNFR-p75 and sCD25 were elevated in the CSF of ADC patients and of the 11 patients with other CNS infections, whereas CSF-levels of the specific T cell marker sCD27 were lower in patients with ADC as compared to the control subjects with and without other CNS infections. This pattern suggests a relative failure of eliciting a T cell-mediated immune response intrathecally in patients with ADC.

Neurologic syndromes

It is now well recognized that HIV-1 associated CNS disease may complicate the course of HIV-1 infection and AIDS in infants and children. It is also well recognized that the neurologic dysfunction in these young patients adds significantly to the morbidity of the disease and is often a devastating complication. It is apparent that HIV-1 CNS infection in infants and young children is complicated by numerous developmental issues. The effects, direct and indirect, of HIV-1 on the developing nervous system must be considered. The effects of HIV-1 on the immature immune system must also be considered. Moreover, the possible effects of HIV-1 on the many complex interactions between these two systems during development will clearly also require investigation. In order to care for these children and to design rational approaches for treatment and prevention, it is now critical to develop a better understanding of how HIV-1 affects the developing nervous system.

Molecular mimicry accompanying HIV-1 infection: human monoclonal antibodies that bind to gp41 and to astrocytes

Monoclonal antibodies that bound to HIV gp41 and cross-reacted with astrocytes were recovered from the blood of three patients infected with HIV-1. Mapping of the specificity of these monoclonal antibodies, using synthetic gp41 peptides, located their epitope to amino acids 644-663 and established their conformation dependence. Six other human monoclonal anti-HIV antibodies were found to bind to HIV gp41 or gp120 but not to reactive astrocytes in brain tissue. Sharing of linear or conformational protein determinants between disparate viral and host proteins is termed molecular mimicry. The consequences of such mimicry by anti-viral antibodies interacting with astrocytes may play a role in the dementia of AIDS patients since a major function of astrocytes is to maintain the appropriate milieu for neuronal function. The finding of such cross-reactive antibodies adds to the evidence for a possible autoimmune pathogenesis in some of the disease manifestations accompanying HIV infection.

Human immunodeficiency virus type 1 infection of the nervous system: pathogenetic mechanisms

Human immunodeficiency virus type 1 (HIV-1) infection of the central nervous system is associated with characteristic virological, clinical, and neuropathological findings in adults and children. Productive infection in the brain and spinal cord occurs in blood-derived macrophages, resident microglia, and multinucleated giant cells. Previous work implicated indirect mechanisms for neurotoxicity by HIV-1 gene products or by factors secreted from HIV-1--infected macrophages. However, this cannot explain the paradox between the small numbers of infected cells and the widespread tissue pathology. Based on recent studies from our laboratories, we suggest that HIV-1--infected macrophages can initiate neurotoxicity, which is then amplified through cell-to-cell interactions with astrocytes. Macrophage-astrocyte interactions produce cytokines tumor necrosis factor-alpha and interleukin-1 beta and arachidonic metabolites that cause astroglial proliferation and neuronal injury. Inevitably, the astrogliosis serves to amplify these cellular processes while brain infection maintains itself in macrophage and microglia and possibly in astrocytes (by restricted infection). These findings, taken together, provide fresh insights into how low numbers of productively infected cells could elicit progressive and devastating neurological impairment during HIV-1 disease, and suggest therapeutic strategies to interrupt the pathological process.

Predictive value of neurological abnormalities in HIV 1 patients in the early stages of the infection

A longitudinal clinical neurological and electrophysiological follow-up study was carried out on 31 HIV1 seropositive outpatients in the asymptomatic or LAS stages of the infection (CDC II-III). The results of clinical examination and multimodal evoked potentials (EP) recording showed a high percentage of abnormalities (42% and 39% of cases respectively); in a statistically significant number of subjects these abnormalities were predictive of subsequent immunological deterioration, thus demonstrating the close relationship between neurological and immunological functions in HIV1 infection.

Pediatric HIV infection: a neuropsychological and educational challenge

Pediatric acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection will soon be the primary infectious cause of perinatally acquired developmental disabilities in the United States. HIV encephalopathy and a variety of opportunistic infections, neoplasms, and vascular changes associated with pediatric HIV infection create a high probability of neuropsychological impairment among preschool and school-age children infected perinatally. Although the use of antiretrovirals may moderate some of the functional difficulties faced by these children, specific neuropathological and neuropsychological deficits are likely to remain. Treatments that prevent the central nervous system (CNS) effects of HIV have yet to be identified. As the epidemic progresses among women of child-bearing age, well-controlled developmental studies are needed to further clarify the relationship between HIV and child development, and to aid professionals in developing appropriate, school-based educational plans.

Neuropsychologic functioning of human immunodeficiency virus-infected children with hemophilia

Efforts to detect subtle but objective neuropsychologic deficits could clarify the early involvement of the central nervous system and the progression of human immunodeficiency virus (HIV) infection in older children and young adolescents. Baseline examinations of 63 children and adolescents with hemophilia were conducted by examiners unaware of HIV status or staging or of our study's major hypotheses. They measured six domains of neuropsychologic functioning (motor, language, memory, attention, visual processing, and problem solving), and no differences between groups of similar age, race, and socioeconomic status defined by HIV seropositivity (n = 25) and HIV seronegativity (n = 38) were revealed. A high incidence of subtle neuropsychologic deficits relative to (1) age norms and (2) individual cognitive potential was found on measures of motor performance, attention, and speeded visual processing within both infected and uninfected groups. On the basis of these baseline data, it seems premature to attribute early, subtle neuropsychologic deficits in seropositive children with hemophilia to the central nervous system effects of HIV infection.

Pathogenesis of virus-induced demyelination

Demyelination is a component of several viral diseases of humans. The best known of these are subacute sclerosing panencephalitis (SSPE) and progressive multifocal leukoencephalopathy (PML). There are a number of naturally occurring virus infections of animals that involve demyelination and many of these serve as instructive models for human demyelinating diseases. In addition to the naturally occurring diseases, many viruses have been shown to be capable of producing demyelination in experimental situations. In discussing virus-associated demyelinating disease, the chapter reviews the architecture and functional organization of the CNS and considers what is known of the interaction of viruses with CNS cells. It also discusses the immunology of the CNS that differs in several important aspects from that of the rest of the body. Experimental models of viral-induced demyelination have also been considered. Viruses capable of producing demyelinating disease have no common taxonomic features; they include both DNA and RNA viruses, enveloped and nonenveloped viruses. The chapter attempts to summarize the important factors influencing viral demyelination, their common features, and possible mechanisms.

Cytokines and arachidonic metabolites produced during human immunodeficiency virus (HIV)-infected macrophage-astroglia interactions: implications for the neuropathogenesis of HIV disease

Human immunodeficiency virus (HIV) infection of brain macrophages and astroglial proliferation are central features of HIV-induced central nervous system (CNS) disorders. These observations suggest that glial cellular interactions participate in disease. In an experimental system to examine this process, we found that cocultures of HIV-infected monocytes and astroglia release high levels of cytokines and arachidonate metabolites leading to neuronotoxicity. HIV-1ADA-infected monocytes cocultured with human glia (astrocytoma, neuroglia, and primary human astrocytes) synthesized tumor necrosis factor (TNF-alpha) and interleukin 1 beta (IL-1 beta) as assayed by coupled reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and biological activity. The cytokine induction was selective, cell specific, and associated with induction of arachidonic acid metabolites. TNF-beta, IL-1 alpha, IL-6, interferon alpha (IFN-alpha), and IFN-gamma were not produced. Leukotriene B4, leukotriene D4, lipoxin A4, and platelet-activating factor were detected in large amounts after high-performance liquid chromatography separation and correlated with cytokine activity. Specific inhibitors of the arachidonic cascade markedly diminished the cytokine response suggesting regulatory relationships between these factors. Cocultures of HIV-infected monocytes and neuroblastoma or endothelial cells, or HIV-infected monocyte fluids, sucrose gradient-concentrated viral particles, and paraformaldehyde-fixed or freeze-thawed HIV-infected monocytes placed onto astroglia failed to induce cytokines and neuronotoxins. This demonstrated that viable monocyte-astroglia interactions were required for the cell reactions. The addition of actinomycin D or cycloheximide to the HIV-infected monocytes before coculture reduced, > 2.5-fold, the levels of TNF-alpha. These results, taken together, suggest that the neuronotoxicity associated with HIV central nervous system disorders is mediated, in part, through cytokines and arachidonic acid metabolites, produced during cell-to-cell interactions between HIV-infected brain macrophages and astrocytes.

Blood-brain barrier abnormalities in the acquired immunodeficiency syndrome: immunohistochemical localization of serum proteins in postmortem brain

Abnormalities in the blood-brain barrier (BBB) may be important in mediating some of the tissue damage that accompanies human immunodeficiency virus (HIV) infection of the brain, as well as in facilitating viral entry into the central nervous system. Accordingly, immunohistochemical detection of fibrinogen (FIB) and immunoglobulin G (IgG) was used as a marker of vascular permeability in formalin-fixed, paraffin-embedded brains of patients with acquired immunodeficiency syndrome (AIDS) who had HIV encephalitis (HIVE) (n = 17) and those who did not have HIVE (n = 16); nonimmunosuppressed patients served as control subjects (n = 22). The sex ratios and postmortem intervals were similar in all groups (p > 0.05), but the age of the two AIDS groups were younger than the control group (43.2 and 40.9 versus 62.5 yr; p < 0.05). The two AIDS groups had higher immunostaining for FIB and IgG than the control group (p < 0.001 and p < 0.0001, respectively) but did not differ from one another. Furthermore, the two AIDS groups had a significantly higher incidence of combined extravasation of both FIB and IgG, whereas the control group had a significantly higher incidence of negative staining for both proteins (p < 0.002). More than 95% of the microglial nodules of HIV were negative for serum proteins; however, all focal lesions with tissue necrosis, including lymphoma, opportunistic infections, and HIV (rarely), contained extravasated serum proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal fluid (CSF) analyses in HIV-1 primary neurological disease

This paper will focus on CSF findings in HIV-1 Neurological Disease (ND). Why use CSF as exploration window of the HIV-CNS involvement? Traditionally, CSF analysis has been an effective diagnostic method as well as a means of monitoring treatment in several infectious and immune pathologies of the CNS. Consequently there is an abundance of mature background information [113, 145, 147] particularly in terms of detecting infectious agents, using IgG findings as immunological indexes, and utilizing CSF findings to map the evolution of ND. We will explore the papers that utilize CSF variables as dependent measures to explore the effects of HIV disease, particularly HIV ND, cited in Index Medicus and MEDLINE data base, and published in Spanish, Italian and English, between 1985 to 1991. We will restrict our review to those studies that exclude HIV cases with CNS opportunistic infections or neoplasms, and thus focus on what the CSF can tell us about the primary effects of HIV on the brain as defined above. The primary long-term goal is to find some elements of the CSF that would lead to an understanding of the etiopathogenesis of HIV ND. However, an almost equally important aim is to determine which CSF variables may be clinically predictive of HIV ND occurrence and progression. The latter variables can also be expected to provide the best measures of HIV ND treatment efficacy. This is particularly important since it is our contention that treatment of HIV ND will eventually be initiated and monitored on the basis of laboratory markers of HIV ND, most likely from the CSF. Finally, this summarized information would be useful in drafting a CSF profile in order to have a reference pattern for cases with complications. The data of this review will be broken down, when the information permits, according to clinical stage and presence or absence of clinical manifestations of ND.

The neuropathology of pediatric acquired immunodeficiency syndrome

Central nervous system disease has emerged as an important manifestation of acquired immunodeficiency syndrome in both the adult and pediatric populations, with neurologic abnormalities occurring in up to 90% of pediatric patients in some series. Neuropathologic studies, based primarily on the autopsy, have provided valuable insights into the spectrum and pathogenesis of acquired immunodeficiency syndrome-associated neurologic disorders, including primary human immunodeficiency virus encephalopathy and as the spectrum of infectious, neoplastic, and cerebrovascular diseases that may complicate the course of acquired immunodeficiency syndrome. Progressive encephalopathy represents the single most common neurologic disorder in pediatric acquired immunodeficiency syndrome and appears to be caused in most cases by direct infection in brain parenchyma by human immunodeficiency virus. Central nervous system lymphoma and cerebrovascular disease continue to account for most focal central nervous system lesions in the pediatric population. In contrast to adults with acquired immunodeficiency syndrome, opportunistic central nervous system infections remain relatively uncommon in the pediatric population. Our understanding of acquired immunodeficiency syndrome-associated neurologic disease remains far from complete. A plea is made for regular postmortem examination of the central nervous system in all patients dying with human immunodeficiency virus infection.

Acquired immunodeficiency syndrome and the child's central nervous system

Human immunodeficiency virus-1 (HIV-1) associated central nervous system disease may complicate the course of HIV-1 infection in infants and children. Neurologic dysfunction in these young patients adds significantly to the morbidity of the disease and is often a devastating complication. It is apparent that HIV-1 infection in infants and young children is complicated by numerous developmental parameters. The developmental stage of the nervous and immune systems when exposed to the virus is likely to interact in complex ways with HIV-1 variables. In order to care for these children and to design rational approaches for treatment and prevention, it is now critical to develop a better understanding of how HIV-1 affects the developing nervous system.

Cytokine regulation of interleukin-6 gene expression in astrocytes involves activation of an NF-kappa B-like nuclear protein

The cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) induce interleukin-6 (IL-6) gene expression in astrocytes. The molecular mechanism(s) by which these cytokines activate IL-6 expression was examined by transient transfection of the human IL-6 promoter linked to the reporter gene CAT (IL-6-CAT) in primary rat astrocytes. We show that both IL-1 beta and TNF-alpha exert their effects through the IL-6 promoter to increase CAT activity, indicating that the cytokines act at the transcriptional level. Use of deletion mutants revealed that the NF-kappa B-like binding site is required for cytokine induction of IL-6 promoter activity. The correlary effects of IL-1 beta and TNF-alpha on DNA-binding proteins specific for this element were examined. Treatment of astrocytes with either cytokine leads to a rapid activation (15 min) of a nuclear protein which specifically complexes with the NF-kappa B-like binding region in the IL-6 promoter. These results suggest that TNF-alpha and IL-1 beta activate IL-6 gene expression in astrocytes by a mechanism(s) involving activation of an NF-kappa B-like protein.

Lack of autologous neutralizing antibodies in the cerebrospinal fluid of HIV-1 infected individuals

The cerebrospinal fluids (CSF) and sera from HIV-1-infected individuals at different clinical stages were monitored for neutralizing activity against CSF-derived HIV-1 isolates. None of the CSF samples and only one of seven serum samples could neutralize the autologous CSF isolate. CSF samples collected one to two years later from the same patients also lacked autologous neutralizing antibodies against these isolates. However, some CSF samples were able to neutralize heterologous CSF isolates albeit in low titers. HIV antibody positive control sera could readily neutralize all of the CSF isolates demonstrating that these isolates were not resistant to neutralization per se. IgG antibodies against the HIV-1 envelope protein and, specifically, against the V3 loop of HIV-1 gp120 (MN) were present in some CSF samples, although the samples lacked neutralizing activity. In summary, this study demonstrates a lack of autologous neutralizing antibodies in CSF samples when assayed against CSF-derived HIV-1 isolates.

Cytokine expression in the brain during the acquired immunodeficiency syndrome

The pathogenesis of central nervous system (CNS) disease in acquired immunodeficiency syndrome (AIDS) is poorly understood but may be related to specific effects of the immune system. Cytokines such as tumor necrosis factor and interleukin-1 may have toxic effects on CNS cells and have been postulated to contribute to the pathogenesis of the neurological complications of human immunodeficiency virus (HIV) infection. To characterize viral and immunological activity in the CNS, frozen specimens taken at autopsy from the cerebral cortex and white matter of HIV-seropositive and -seronegative individuals were stained immunocytochemically for mononuclear cells, major histocompatibility complex (MHC) antigens, HIV, astrocytes, and the cytokines interleukin-1 and -6, tumor necrosis factor-alpha and -beta, and interferon gamma. Levels of soluble CD4, CD8, and interleukin-2 receptor, as well as interferon gamma, tumor necrosis factor-alpha, beta 2-microglobulin, neopterin, and interleukin-6 and -1 beta were assayed in the cerebrospinal fluid and plasma of many of these individuals during life. The HIV-seropositive group included individuals without neurological disease, those with CNS opportunistic infections, and those with HIV encephalopathy. Perivascular cells, consisting primarily of macrophages with some CD4+ and CD8+ T cells and rare B cells, were consistently MHC class II positive. MHC class II antigen was also present on microglial cells, which were frequently positive for tumor necrosis factor-alpha. HIV p24 antigen, when present, was found on macrophages and microglia. Endothelial cells were frequently positive for interleukin-1 and interferon gamma and less frequently for tumor necrosis factor and interleukin-6. There were gliosis and significant increases in MHC class II antigen, interleukin-1, and tumor necrosis factor-alpha in HIV-positive patients compared to HIV-negative brains. Cerebrospinal fluid from most of the patients tested had increased levels of tumor necrosis factor, beta 2-microglobulin, and neopterin. There was no correlation in HIV-positive individuals between levels of cytokines and the presence or absence of CNS disease. These data indicate that there is a relative state of "immune activation" in the brains of HIV-positive compared to HIV-negative individuals, and suggest a potential role for the immune system in the pathogenesis of HIV encephalopathy.

Auditory function in patients infected with the human immunodeficiency virus

A prospective study of auditory function in 18 HIV positive male patients at different CDC (Centres for Disease Control) stages was undertaken. One-third had abnormalities on either auditory evoked response testing or pure tone audiometry. No correlation was found between interwave latencies I-V, I-III, III-V and stage of disease determined either clinically or by T-cell subset. There was a weak correlation between pure tone averages at 1,2,4 kHz and 2,4,8 kHz and T-cell subset ratio in CDC Group IV disease (Rs = 0.56 and 0.57 respectively; P less than 0.05). Abnormalities of BSER were similar to those previously reported in HIV infection, and suggest isolated changes within the brain-stem.

Clinical manifestations, management and therapy of HIV infection in children

Perinatal infection accounts for the majority of cases of HIV infection in children both in developed and developing countries. Transmission may occur in utero, intrapartum or postpartum as a result of breast-feeding. The actual risk of transmission through breast-feeding is unknown. The majority of infants reported to be infected through breast milk have been infected as a result of a recently acquired HIV infection in the mother. Infants with HIV infection frequently present with clinical symptoms early in life. There is a broad spectrum of clinical findings in paediatric HIV infection, with opportunistic infections and multiorgan system involvement being common. The management of infants born to seropositive mothers includes routine paediatric care as well as careful clinical and laboratory monitoring for evidence of HIV infection. Infants who are seronegative with normal clinical and immunological findings at 18 months of age are considered uninfected. The prognosis and outcome of infants with HIV infection have improved considerably with earlier diagnosis and the availability of specific antiviral therapy. Modalities of therapy include frequent medical evaluation, aggressive diagnosis and treatment of infection, prophylaxis for Pneumocystis carinii infection, the use of intravenous gamma-globulin and specific antiviral therapy, such as zidovudine, didanosine or other drugs in development through clinical trials. HIV infection in children is a chronic illness and requires a comprehensive, family-oriented approach to care. With longer survival, children require support systems and an atmosphere of care and understanding to give them a good quality of life as well as prolonged survival.

Cerebrospinal fluid anti-cerebellar soluble lectin antibodies in human immunodeficiency virus type 1 infection

Cerebrospinal fluid samples from 14 human immunodeficiency type 1 (HIV-1) seropositive patients in various stages of HIV infection were tested for the presence of autoantibodies to an endogenous manose-binding protein, the cerebellar soluble lectin (CSL), which has recently been found to be detected in a high proportion of patients with multiple sclerosis. An immunoblotting test was used with rat CSL as antigen. Seven patients were positive for anti-CSL and seven were negative. The seven anti-CSL-positive patients had signs of intrathecal immunoglobulin G production measured as an elevated IgG index, while the seven anti-CSL-negative patients had a normal IgG index. There was no apparent relation between infectious stage and the presence of anti-CSL. Immunological reactions such as anti-CSL autoantibodies may be a similar pathogenic mechanism in HIV and multiple sclerosis brain disease.

A new complement fixation test for the diagnosis of neurocysticercosis in cerebrospinal fluid

As a modification of the classical complement fixation test, a new test for immunodiagnosis in cerebrospinal fluid (CSF) was developed. When the assay was used for the diagnosis of neurocysticercosis in 149 CSF samples from patients and 1036 from controls, results showed 93% concordance with positives and 97% with negatives when compared with the results obtained by ELISA; in addition, it was positive in 12 of 16 cases of neurocysticercosis in which negative results had been obtained by ELISA. The new complement fixation test is particularly useful in CSF because of the immunological peculiarities of the subarachnoid space, where local synthesis of oligoclonal antibodies is induced by infectious agents. Reagents used for the assay are easy to produce and preserve, and the test is inexpensive, reliable and easy to perform. As this test detects the immunobiological consequence of the antigen-antibody reaction, it can be used in conjunction with other assays, such as ELISA, that measure the reaction directly, thus increasing the diagnostic possibilities. It may also be used where financial or technical limitations hinder access to other immunodiagnostic tests.

Immunoglobulin G subclass preference of intrathecally produced HIV-specific oligoclonal antibodies

Cerebrospinal fluid (CSF) and serum samples from 16 HIV-seropositive subjects were examined by ELISA and isoelectric focusing for the presence of HIV-specific immunoglobulin G (IgG) subclass antibodies. Autochthonous synthesis of IgG in the CSF was demonstrated in 11 patients. Intrathecally synthesized antibodies specific for individual HIV structural proteins were largely restricted to IgG1 (10 of 11 patients). One patient revealed additional local synthesis of IgG2 antibodies related to HIV-p15. In another patient locally produced antibodies specific for HIV consisted entirely of IgG4. In this patient amounts of locally produced antibodies were too low to be detected by routine procedures (calculation from an evaluation graph). No local synthesis of HIV-related IgG3 was demonstrated in any patient. Further studies will be needed to show whether determination of IgG-subclass-restricted antibodies to HIV is of prognostic value.

Acute infection with human immunodeficiency virus presenting with neurogenic urinary retention

Several neurological presentations of acute primary infection with HIV have recently been described. A previously unrecognised presentation with neurogenic retention of urine and sacral sensory loss is reported. The case is discussed in the context of other neurological syndromes associated with seroconversion to HIV, and of other viral causes of acute retention of urine. The importance of considering the possibility of primary HIV infection in a wide range of self-limiting neurological disorders is emphasised.

Neocortical damage during HIV infection

Clinical and pathological evidence of subcortical central nervous system (CNS) damage is observed commonly in patients with human immunodeficiency virus (HIV) encephalitis. Whether other CNS regions are also affected has not been well studied. We report neocortical damage in patients with HIV encephalitis. Using quantitative techniques, we demonstrate statistically significant thinning of the neocortex, with a loss of large cortical neurons. Qualitative and quantitative assessments of neocortical neuropil reveal a loss of synaptic density and vacuolation of dendritic processes. Failure to demonstrate an association of these changes with the presence of HIV antigens suggests that neocortical damage may be an indirect effect of HIV infection of the CNS.

Kappa light chain predominance in serum and cerebrospinal fluid from human immunodeficiency virus type 1 (HIV-1)-infected patients

We measured kappa/lambda light chain ratios of Ig and IgG in 41 serum and 34 cerebrospinal fluid (CSF) samples from 47 patients at different clinical stages of human immunodeficiency virus type 1 (HIV-1) infection and in serum and CSF samples from control subjects. Both ratios were more elevated in HIV-1 seropositive subjects than controls. The elevation was more evident in samples from asymptomatic seropositive patients (ASP) than those from patients with acquired immunodeficiency syndrome (AIDS). In addition, there was a statistically significant elevation of Ig kappa/lambda ratios in ASP CSF compared to serum. We also delineated the light chain composition of oligoclonal IgG bands (OCB) by isoelectric focusing followed by immunofixation in CSF and serum samples from selected ASP and patients with AIDS who had neurological involvement. Five of six AIDS and all seven ASP samples had IgG OCB exclusively or predominantly of the kappa type. Four IgG OCB of the lambda type and one free lambda chain band were seen in CSF from a pediatric AIDS patient. The presence of an abnormally elevated kappa/lambda ratio correlated with the presence of IgG kappa OCB (p less than 0.02). We conclude that HIV-1 infection is associated with a kappa light chain predominance and with OCB mainly composed of kappa light chains.

Neurotropism of human immunodeficiency virus

Three major characteristics of human immunodeficiency virus (HIV) infection define HIV as neurotropic. 1) Clinically, distinct neurological syndromes are associated with HIV infection and 2) presence of the virus as well as 3) pathological changes can be demonstrated in the central nervous system. Spread of HIV to the brain seems to be the general rule. Virus expression appears to be restricted during the asymptomatic period but increases with severity of HIV infection. Whether this reflects the emergence of virus variants with increased replicative capacity in brain cells has yet to be elucidated.

HIV encephalopathy: incidence, definition and pathogenesis. Results of a Swiss collaborative study

The incidence of HIV encephalopathies was determined in an ongoing consecutive autopsy study. Among 345 patients who died from AIDS in Switzerland during 1981-1990, 68 (19%) showed morphological evidence of HIV encephalopathy. Two major histopathological manifestations were observed. Progressive diffuse leukoencephalopathy (PDL) was present in 33 cases and is characterized by a diffuse loss of myelin staining in the deep white matter of the cerebral and cerebellar hemispheres, with scattered multinucleated giant cells but little or no inflammatory reaction. Multinucleated giant cell encephalitis (MGCE) was diagnosed in 32 cases; it's hallmarks are accumulations of multinucleated giant cells with prominent inflammatory reaction and focal necroses. In 3 patients both types of lesions overlapped. Brain tissue from 27 patients was analyzed for the presence of HIV gag sequences using the polymerase chain reaction (PCR) with primers encoding a 109 base pair segment of the viral gene. Amplification succeeded in all patients with clinical and histopathological evidence for HIV encephalopathy but was absent in AIDS patients with opportunistic bacterial, parasitic and/or viral infections. Potential mechanisms by which HIV exerts it's adverse effects on the human CNS are discussed.

Common immunologic determinant between human immunodeficiency virus type 1 gp41 and astrocytes

Monoclonal antibodies against a synthetic 12-amino-acid peptide that comprises the immunodominant domain of human immunodeficiency virus type 1 gp41 (amino acids 598 through 609) reacted with astrocytes found in human and rodent central nervous system tissue. The monoclonal antibodies bound to a 43-kDa protein found in central nervous system tissue preparations. These results indicate that human immunodeficiency virus type 1 gp41 contains a common epitope with astrocytes and that an immune response to human immunodeficiency virus type 1 gp41 could generate antibodies that are cross-reactive to astrocytes. Furthermore, anti-astrocyte antibodies, which were directed at a common epitope with the gp41 sequence, were found to be present in cerebrospinal fluid from some AIDS patients with central nervous system complications. Astrocytes regulate the environment for appropriate neuronal function, and astrocyte hyperactivity (astrocytosis) is known to be the common and early pathologic event in brains from patients with central nervous system AIDS. We suggest that antibody-induced effect(s) on astrocytes could lead to the physiologic neuronal dysfunctions observed in AIDS patients.

Intrathecal IgG synthesis and specificity of oligoclonal IgG in patients infected with HIV-1 do not correlate with CNS disease

The CSF/serum immune response to HIV 1 was studied in 24 patients admitted for investigation. The level of antibody to HIV-1 and specificity of oligoclonal IgG were determined in blood and cerebrospinal fluid (CSF). The majority of patients demonstrated elevated levels of intrathecal IgG synthesis, with levels of HIV-1-specific antibody frequently being significantly higher in CSF than in serum. In 16 of 21 patients the CSF/serum antibody ratio indicated active intrathecal synthesis. Oligoclonal banding was present in CSF from all 24 patients. Immunoprinting of serum and CSF demonstrated antigenic specificity (p24, gp 160, RT) of the clonal antibodies in all of 12 patients though the patterns of reactivity in CSF did not necessarily correspond with that of serum. Although a specific association of particular patterns with HIV CNS disease was not found we feel that these markers should be included in longitudinal studies of HIV-related diseases of the CNS. The specificity of oligoclonal antibodies, both in CSF and in serum was demonstrated, and this specificity may be a useful marker for longitudinal studies in HIV-1 antibody-positive asymptomatic patients.

The use of recombinant antigens in ELISA procedures for the quantification of intrathecally produced HIV-1-specific antibodies

An ELISA procedure is described for the quantification of intrathecally synthesized immunoglobulin G antibodies to human immunodeficiency virus (HIV) antigens. Recombinant p17, p24, endonuclease (END), reverse transcriptase (RT), a peptide from the transmembrane region of gp41 (ENV80) and a fusion protein containing HIV-1 and HIV-2 epitopes were compared with a commercially available ELISA. Using a reference serum, antibodies in serum and cerebrospinal fluid (CSF) to all of the antigens could be measured quantitatively in a reliable and reproducible fashion. Despite the fact that the titer varied up to 10(5)-fold between CSF and serum, interassay variability ranged from 3.87% for p17 to 8.41% for RT and intra-assay variability varied from 3.9% +/- 1.2% for p17 to 14.3% +/- 3.9% for the commercial ELISA. Antibody specificity indices (ASI) obtained by relating CSF/serum titers with reference to the corresponding IgG concentrations can be used to detect intrathecal synthesis of virus specific antibodies.

Neopterin and beta 2-microglobulin and the assessment of intra-blood-brain-barrier synthesis of HIV-specific and total IgG

In HIV-seropositive patients, we evaluated the clinical utility of measuring combinations of serum and CSF levels of neopterin and beta 2-microglobulin (beta 2-M) (by RIA), as well as the intra-blood-brain-barrier (IBBB) IgG synthesis rate, IgG index, and HIV antibody index (by rate nephelometry, EIA, and formulae) for the assessment of HIV infection of the CNS. We studied paired sera and CSF from 31 HIV-seropositive patients: asymptomatic (16), ARC (12), and AIDS (3). A normal serum neopterin level predicts normal levels of serum beta 2-M, CSF neopterin, or CSF beta 2-M in 90%, 100%, and 100%, respectively, of our patients. An elevated serum neopterin level predicts an elevated level of serum beta 2-M or CSF neopterin in 81% and 62%, respectively, of cases. The HIV antibody index and IBBB IgG synthesis rate or IgG index must be determined separately because they do not predict each other and are not predicted by levels of neopterin or beta 2-M.

Induction and regulation of interleukin-6 gene expression in rat astrocytes

Cells that produce interleukin-6 (IL-6) require the presence of signaling molecules since this cytokine is not normally constitutively expressed. It is now established that astrocytes produce IL-6; however, the precise inducing molecules and the kinetics of their action have not yet been clearly identified. In the current study, we show that either interleukin-1 beta (IL-1 beta) or tumor necrosis factor-alpha (TNF-alpha) exert a strong inducing signal for IL-6 in primary rat astrocytes. When the two cytokines are added together the response is synergistic, suggesting that each cytokine may induce IL-6 gene expression by different pathways. Interferon-gamma (IFN-gamma) does not affect IL-6 expression although if it is added in conjunction with IL-1 beta, an augmented induction of IL-6 occurs. In addition to the cytokines, bacterial lipopolysaccharide (LPS) and the calcium ionophore, A23187, induce IL-6 expression. IL-6 expression can be blocked by the glucocorticoid analogue, dexamethasone. IL-6 induction by LPS/Ca2+ ionophore is more sensitive to the suppressive effects of dexamethasone than is IL-6 induction by TNF-alpha/IL-1 beta. Cycloheximide (CHX), an inhibitor of protein synthesis, markedly increased levels of IL-6 mRNA in both unstimulated and stimulated astrocytes, indicating that ongoing protein synthesis is not required for astrocyte IL-6 gene expression. We propose that astrocyte-produced IL-6 may have a role in augmenting intracerebral immune responses in neurological diseases such as multiple sclerosis (MS), AIDS dementia complex (ADC), and viral infections. These diseases are characterized by infiltration of lymphoid and mononuclear cells into the central nervous system (CNS), and intrathecal production of immunoglobulins. IL-6 may act to promote terminal differentiation of B cells in the CNS, leading to immunoglobulin synthesis.

Fine analysis of intrathecally synthesized anti-HIV IgG1-4 by peptide mapping

ELISAs utilizing HIV-derived synthetic peptides as antigen were used to analyze serum and CSF IgG1-4 from 15 HIV infected patients. Intrathecally synthesized IgG1-4 reactive to one or several HIV-derived peptides were detectable in 12 of 15 patients. Intrathecally synthesized anti-peptide IgG was more common in patients with neurological symptoms than in those without. CSF reactivity not paralleled by serum reactivity was detected to HIV-peptides in 4 patients. IgG1-4 to gp41 was relatively more frequent in the CNS than IgG1-4 to gag. Intrathecal IgG synthesis to the gp120 peptide was not detected in any patient. The anti-peptide responses were dominated by IgG1. Intrathecal IgG2 and 4 synthesis was found in 2 and 5 patients, respectively. IgG3 synthesis intrathecally was not detected in any of the patients. ELISAs detecting IgG1-4 to HIV-derived synthetic peptides are feasible to analyze the fine specificities of intrathecal IgG. The mapping of idiotypes and isotypes of IgG synthesized in the CNS will increase the possibilities of elucidating B-cell regulation in the CNS and which viral components evoke immune responses.

Intrathecal synthesis of immunoglobulins in patients with Alzheimer's disease

Serum and cerebrospinal fluid (CSF) of 45 patients with Alzheimer's disease (AD) and 24 healthy controls were examined in order to investigate the possibility of an intrathecal synthesis of immunoglobulins in AD. The group of AD patients showed higher IgG and IgM indices than the control group. Five (11%) AD patients had an intrathecal IgG synthesis and 7 (15%) an intrathecal IgM synthesis. In total, 12 (26%) AD patients had an intrathecal immunoglobulin synthesis, while there was none among the controls. This finding supports the hypothesis that immunological mechanisms may play a role in the etiology and/or pathogenesis of Alzheimer's disease, at least in a subgroup of patients.

Cerebrospinal fluid interleukin-6 activity in HIV infection and inflammatory and noninflammatory diseases of the nervous system

Interleukin-6 (IL-6) activity was measured in the cerebrospinal fluid (CSF) of patients at different stages of human immunodeficiency (HIV) virus infection and of patients with multiple sclerosis (MS) or other inflammatory (OID) and noninflammatory neurological diseases (OND). In the advanced stages of HIV infection and in OID, IL-6 was detected more frequently (80 and 75% of the cases) and at higher concentrations than in the early stages of HIV infection. MS and OND (44, 48, and 44% of cases). Analysis of CSF and paired sera indicated that IL-6 production can be compartmentalized to either of the fluids. Evidence that altered blood-brain barrier functions can, at least in part, influence the CSF IL-6 levels was found in OID patients. No association was evident between intrathecal immunoglobulin synthesis and CSF IL-6 levels. Interleukin-1 (IL-1) levels were detectable in a minority of the samples from neurological patients; one OID patient had high levels of both CSF IL-1 and IL-6.

Intrathecal synthesis of anti-HIV antibodies in AIDS patients

We studied the production within the CNS of anti-HIV antibodies, of non-specific IgG, and the presence of HIV antigens in the serum and CSF of 28 HIV infected patients belonging to group IV in the Center for Disease Control classification. CSF and serum were diluted under optimal conditions to equalize their IgG content, to enable us to better interpret serum and CSF reactivity by means of Western blot and ELISA. Under these conditions, no patient displayed a limited immunological response profile in CSF as compared to serum. On the contrary, there was intrathecal synthesis (ITS) of anti HIV-antibodies in Western blot test in 21 patients for gp160 and ITS was demonstrable for env, gag, and pol products. ITS of anti-HIV antibodies occurred in 17 patients when measured by ELISA. ITS of non specific IgG and HIV-antigens in CSF were less frequent. A marked anti-HIV response is evident in the CSF-CNS compartment in the later phases of the HIV infection.

Early HIV-related neuropsychological impairment: relationship to stage of viral infection

Sixty male outpatients with no past neuropsychiatric history were examined for evidence of early HIV-related neuropsychological impairment. Significant cognitive deficit, as measured by the RAVLT and WAIS-R Digit Symbol Substitution tests, and moderate correlation with indices of immune function, were observed in a group of patients with AIDS-Related Complex [ARC]. Patients with asymptomatic HIV-infection demonstrated no significant differences in performance compared to a group of HIV-seronegative controls. No significant group differences in age, education, predicted-IQ or self-rated depression and anxiety were observed. These results support the hypothesis that HIV-related cognitive disturbance occurs within the context of immunosuppression.

Brain imaging in acquired immunodeficiency syndrome dementia complex

Human immunodeficiency virus (HIV) infections are accompanied by many different types of neurological complications. Opportunistic infections and neoplasms, particularly lymphoma, are often an underlying cause for these complications in patients with acquired immunodeficiency syndrome (AIDS). Frequently, these can be detected by cerebrospinal fluid (CSF) examination, double-dose contrast transmission computed tomography (CT), and/or magnetic resonance imaging (MRI). It has become apparent that the HIV itself is responsible for a significant percentage of neurological disease in the HIV-seropositive individual. The onset may be subtle and may occur before the onset of frank immunosuppression. Diagnosis of HIV encephalitis or AIDS dementia complex (ADC) is complicated by the frequent coexistence of opportunistic infections. Structural neuroimaging (CT or MRI) shows atrophy and in some case white matter abnormalities, but imaging-pathological correlation suggests that these modalities are relatively insensitive to the presence of HIV brain infection. Functional neuroimaging, both 18fluorodeoxyglucose positron emission tomography (PET) for evaluation of glucose metabolism and 123I iodoamphetamine or 99mTc-HMPAO single-photon emission computed tomography (SPECT) for evaluation of cerebral perfusion, can demonstrate abnormalities in the subcortical gray matter structures and the cerebral cortex in patients with ADC. These abnormalities may be observed early in the course of ADC even when MRI is negative and the patient is relatively asymptomatic. Also, PET and SPECT may be useful to follow progression of the dementia or response to therapy.