Neurological complications of acquired immune deficiency syndrome: analysis of 50 patients

Histopathology of the central nervous system in the acquired immunodeficiency syndrome

Histopathologic findings in the central nervous system in 100 autopsy cases of the acquired immunodeficiency syndrome (AIDS) gave evidence of a variety of opportunistic infections and probably of infection by human immunodeficiency virus (HIV). Gliomesenchymal cell nodules (47 per cent of cases) and spongiform alterations with demyelination were common. Vasculitides (8 per cent) and lesions such as acute hemorrhagic leukoencephalitis may be attributable partly to hypersensitivity reactions. Multinucleated cells, including giant cells that could be a hallmark of HIV encephalitis, were common in normal neuropil, in gliomesenchymal cell nodules, near blood vessels, and in cavitating lesions. Degeneration in long tracts (13 per cent) included posterior column demyelination and spongiform change with or without corticospinal tract degeneration. Some long tract degeneration appeared to originate from bilateral degeneration of the internal capsule, and this may be part of the origin of subacute combined degeneration-like changes in AIDS vacuolar myelopathy. Prominent brainstem inflammatory infiltration suggests that the brainstem is a relatively prominent site of infection or immunopathologic activity. Early ependymal lesions in infants and frequent healed ependymal lesions in adults (16 per cent) could be related to the origin and pathogenesis of HIV lesions in the brain. Some characteristic lesions in AIDS encephalitis may result from immune-mediated responses to HIV antigens on neural cell receptors or from cross-reactivity occurring against epitopes common to neural constituents and to hematopoietic cells, with the latter being under direct antiviral attack.

Neurological complications in AIDS

Neurological complications in the acquired immunodeficiency syndrome (AIDS) are an important aspect of this new infectious disease and occur frequently. The existence of neurotropic variants of the human immunodeficiency virus (HIV), the causative agent of AIDS, is probable. Direct infection of the nervous system with HIV leads to a variety of HIV-induced neurological syndromes, the AIDS dementia complex being its most important representative. In addition, a large number of opportunistic infections and malignancies of the nervous system may complicate the disease. Major aspects of the clinical pictures, rational diagnostic approaches and treatment options of the most important sequels of HIV infection of the nervous system are discussed.

Dual infection of the central nervous system by AIDS viruses with distinct cellular tropisms

Human immunodeficiency virus (HIV) is the causative agent of the acquired immune deficiency syndrome (AIDS). A large number of AIDS patients show evidence of neurologic involvement, known as AIDS-related subacute encephalopathy, which has been correlated with the presence of HIV in the brain. In this study, two genetically distinct but related viruses were isolated from one patient from two different sources in the central nervous system: brain tissue and cerebrospinal fluid. Both viruses were found to replicate in peripheral blood lymphocytes, but only virus from brain tissue will efficiently infect macrophage/monocytes. The viruses also differ in their ability to infect a brain glioma explant culture. This infection of the brain-derived cells in vitro is generally nonproductive, and appears to be some form of persistent or latent infection. These results indicate that genetic variation of HIV in vivo may result in altered cell tropisms and possibly implicate strains of HIV with glial cell tropism in the pathogenesis of some neurologic disorders of AIDS.

AIDS and the geriatrician

Ten percent of acquired immune deficiency syndrome (AIDS) cases are in persons over 50 years of age with 25% of these cases in persons over 60, and 4% in persons over 70 years of age. If the present age distribution holds, there will be 27,000 AIDS cases in persons over 50, and 1100 cases in persons over 70 years of age, by 1991. Older persons are more likely to acquire AIDS through blood transfusions than to homosexual exposure or drug abuse. Changes in the management of blood products will benefit older persons. The nearly 1 million elderly homosexual men, who have been sheltered from the virus by their pattern of sexual activity, will face greater risks as the prevalence of the virus and the age of the carriers increases. The underappreciated neurological consequences of human T-cell lymphotrophic virus type III (HTLV-III) infection, subacute encephalitis, vacuolar myelopathy, and psychiatric disorders will be of particular interest to geriatricians who are often consulted to evaluate neurological dysfunction. Geriatricians will need to become familiar with the spectrum of HTLV-III infection and prepared to counsel patients and extended-care facilities.

Myopathy complicating the acquired immune deficiency syndrome

A case of Acquired Immunodeficiency Syndrome complicated by a severe myopathy is reported. All efforts aimed at documenting an infectious etiology for the myopathy were negative. The relationship of myopathy to AIDS is discussed.

CSF protein and cellular profiles in various stages of HIV infection related to neurological manifestations

CSF protein and cellular profiles were studied in 28 HIV-infected patients. Twenty of them had neurological complaints, but only 6 patients had objective neurological deficits such as dementia, ocular motility disorders or polyneuropathy. The serum/CSF HIV antibody ratio was on average lowest in acquired immunodeficiency syndrome (AIDS) (4 patients) and highest or almost normal in lymphadenopathy syndrome (LAS) (11) and asymptomatic seropositivity (ASX) (7), while it varied between these extremes in AIDS-related complex (ARC) (6). However, low values of the ratio were also found in the HIV-infected patients free of neurological symptoms and even in one ASX patient. The CSF IgG index was elevated in all these 4 general stages of HIV infection without any significant differences between them. The CSF/serum albumin ratio was slightly increased in patients with neurological deficits, but this ratio showed no association with any other clinical factor analysed. CSF leucocytes were increased in the early stages of the disease, but later the cellular reaction subsided. HIV was isolated from post mortem brain tissue of two AIDS patients and from the CSF of one of them. The results suggest increased intrathecal virus-specific IgG synthesis, not only in patients with neurological deficits and at advanced stages of infection, but also in neurologically symptom-free subjects and at early infection. The lack of correlation between the increased virus-specific IgG synthesis within the CNS and the presence of neurological symptoms suggests that neurologically "silent" areas of brain white matter are often affected in HIV infection.

HIV antigen in the brains of patients with the AIDS dementia complex

Human immunodeficiency virus infection was identified immunohistochemically in the brains of 8 patients with acquired immune deficiency syndrome dementia complex. Using a monoclonal antibody against a structural viral protein (p25), infection was detected in white matter and basal ganglia in a distribution paralleling that of the major neuropathological abnormalities. Viral antigen was identified principally in perivascular and parenchymal macrophages and in multinucleated cells of macrophage origin that were identified morphologically and by immunocytochemical staining for acid phosphatase isozyme. In 4 of the 8 patients, viral antigen was also detected in acid-phosphatase-negative, process-bearing neuroglial cells; in 2 patients, antigen was detected in basal ganglion cells that were morphologically consistent with neurons and in alkaline-phosphatase-positive cells with elongated nuclei that were most likely of endothelial origin.

Clindamycin in a murine model of toxoplasmic encephalitis

We investigated the efficacy of clindamycin in a murine model of toxoplasmic encephalitis using direct intracerebral inoculation. Clindamycin reduced mortality from 40% in normal mice and 100% in cortisone-treated mice to 0% in both groups. Although we were unable to document appreciable levels of clindamycin in the brains of infected mice, the histological features of cerebral infection were markedly altered. The formation of large numbers of cysts and the intense inflammatory response seen in the brains of normal mice and the unchecked infection and tissue necrosis in the brains of cortisone-treated mice were absent in the brains of clindamycin-treated mice. Enumeration of cysts in the brains of mice 10 weeks after infection revealed a significantly lower number in the clindamycin-treated mice. Spread of infection to other organs was also decreased during clindamycin administration. These observations suggest that clindamycin may have a role in the therapy of toxoplasmic encephalitis.

Infection of brain-derived cells with the human immunodeficiency virus

A malignant glioma cell line was infected with the human T-lymphotropic virus type IIIB isolate of the human immunodeficiency virus. Infection appeared to be latent rather than productive. Through contact with monocytic or lymphoid cells, the virus present in the glioma cells could be transmitted and gave rise to a fully productive infection.

Expression of the T4 molecule (AIDS virus receptor) by human brain-derived cells

Three human cell lines of astrocytic origin were evaluated for expression of a human T-lymphocyte surface glycoprotein, T4, which also serves as a cellular receptor for the human immunodeficiency virus (AIDS virus, HIV). T4 antigen was detected on the cell surface of 2 of these cell lines using monoclonal OKT-4 antibody and flow cytometry. Gene transcripts encoding the T4 molecule were detected by a ribonuclease protection assay in surface T4-positive and -negative cells. Our results suggest that astrocytes may serve as targets for HIV infection in the brain.

Susceptibility of human glial cells to infection with human immunodeficiency virus (HIV)

Three human brain-derived cell lines (including two of astrocytic origin) were exposed in vitro to the human immunodeficiency virus (HIV), the etiologic agent of immunodeficiency in AIDS. In all three lines, HIV transcripts were detected by in situ hybridisation in 20-30% of cells 48 h after infection. Synthesis of virus gag gene products p24 and p55 was demonstrated by immunoblotting. No cytopathic effects typical of HIV-infected human T lymphocytes were observed. Our data indicate that HIV is neurotropic, and support the hypothesis that this virus may infect astrocytes in the brain.

Progressive multifocal leukoencephalopathy in a patient without other clinical manifestations of AIDS

The case is reported of a 46-year-old homosexual LAV/HTLV III seropositive man in whom progressive multifocal leukoencephalopathy was the first and only clinical manifestation of AIDS. The severity and extension of neurological disturbances in AIDS are discussed.

Pleural cryptococcosis in the acquired immune deficiency syndrome

Pleural cryptococcosis is extremely rare. We report the first case of cryptococcal pleural effusion in association with the acquired immune deficiency syndrome. Pleural effusion without the evidence of pulmonary parenchymal involvement was the initial and only clinical finding leading to the diagnosis of disseminated cryptococcosis. The pleural effusion resolved spontaneously prior to amphotericin B therapy.

Cytomegalovirus encephalitis in patients with acquired immunodeficiency syndrome: an autopsy study of 30 cases and a review of the literature

The pathology of cytomegalovirus (CMV) encephalitis was studied at autopsy in thirty patients with acquired immunodeficiency syndrome. Lesions could be segregated into five major categories: microglial nodules, isolated inclusion-bearing cells, focal parenchymal necrosis, necrotizing ventriculo-encephalitis, and necrotizing radiculo-myelitis. Microglial nodules and CMV inclusions were present in all brains. Microglial nodules were found with variable frequency and had greatest density in subcortical grey matter. Only a small percentage (average, 6.5 per cent) contained CMV inclusion-bearing cells. Isolated inclusion-bearing cells unaccompanied by microglial nodules or inflammatory infiltrates were seen in half the patients. CMV inclusions were identified in capillary endothelia, astrocytes, and neurons. Focal CMV necrosis, ventriculo-encephalitis, and radiculo-myelitis were less frequent. The presence of CMV inclusions in capillary endothelia suggests a vascular portal of entry for the virus into the central nervous system. The diffuse ependymal and/or subpial distribution of CMV in several patients suggests additional dissemination via the cerebrospinal fluid. Isolated inclusion-bearing cells may reflect the relative nonpermissiveness of surrounding central nervous system parenchyma for CMV infection.

MRI appearance of AIDS subacute encephalopathy

A case of biopsy documented subacute encephalopathy of AIDS was evaluated by CT and MRI. CT scanning revealed ventriculomegaly and ill-defined nonspecific periventricular white matter hypodensities. MRI, however, demonstrated extensive unequivocal diffuse white matter disease as the cause of the ventriculomegaly. MRI findings in this patient support the preliminary suggestion that MRI is more useful than computed tomography (CT) in demonstrating AIDS subacute encephalopathy.

Neoplastic complications of HTLV-III infection. Lymphomas and solid tumors

Neoplastic disease arose in 29 of 200 patients infected with human T lymphotropic virus type III (HTLV-III) seen at a suburban hospital. Seventeen patients had Kaposi's sarcoma, one of whom also had colon carcinoma. Nine patients had lymphoproliferative disorders (seven lymphomas, one T suppressor cell chronic lymphocytic leukemia, and one multiple myeloma), including three with concomitant Kaposi's sarcoma and one with colon cancer. One other patient had colon cancer, one had a seminoma, and one had pancreatic cancer. Kaposi's sarcoma as a complication of AIDS occurred mainly in homosexuals (17 of 42 homosexuals, one of 17 drug abusers, one of five heterosexually promiscuous patients, and one of six patients who had previously received transfusions). The high-grade lymphomas did not show a predilection for any particular AIDS risk group. Three of four solid tumors arose in elderly AIDS patients. Twenty-five of 75 patients with CDC-defined AIDS had a neoplastic disorder (26 are still alive and may yet demonstrate malignancy). Few other diseases of man have been associated with as high an incidence of neoplastic transformation as occurs with HTLV-III infection.

Autoradiographic localization of T4 antigen, the HIV receptor, in human brain

Using a novel autoradiographic technique and a monoclonal antibody to T4, the entry protein for the AIDS virus HIV, we have determined the distribution of T4 in selected areas of the human brain. T4 was found throughout the human brain in a pattern similar to that seen in squirrel monkey and rat, thus demonstrating a conservation of both the antigen and the antigen distribution. T4 was especially abundant in emotion-mediating areas, such as the hippocampus, which are typically enriched with neuropeptide receptors. In addition, several regions of the cerebral cortex were found to have T4 antigen especially in superficial layers. These data suggest that the psychiatric and neuropathological symptoms presented by AIDS patients may be a result of the direct interaction of the AIDS virus with specific areas of the brain.

CD4 receptor binding peptides that block HIV infectivity cause human monocyte chemotaxis. Relationship to vasoactive intestinal polypeptide

The octapeptide Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr (peptide T) and two structural analogs are potent agonists of human monocyte chemotaxis, evincing identical rank potency orders as was previously shown for their inhibition of human immunodeficiency virus (HIV) envelope binding and T cell infectivity. Chemotactic activity could be inhibited by anti-CD4 monoclonal antibodies (Mabs), but not other mononuclear cell Mabs. The core peptide required for chemotactic activity is a pentapeptide related to the sequence Thr-Thr-Asn-Tyr-Thr. Homologous pentapeptides, identified by computer search, were detected in several other non-HIV-related viruses as well as the neuropeptide vasoactive intestinal polypeptide (VIP). The CD4 molecule, therefore, appears to be a recognition molecule for a small signal peptide ligand whose active sequence is a homolog of peptide T and which may be the neuropeptide VIP.

Leucoencephalopathy with multinucleated giant cells containing human immune deficiency virus-like particles and multiple opportunistic cerebral infections in one patient with AIDS

A 29-year-old homosexual male with AIDS presented with progressive encephalopathy and cytomegalovirus (CMV) pneumonia. Neuropathological examination revealed toxoplasma abscesses in corpus callosum, basal ganglia and cerebellar white matter; demyelinating foci in the parietal white matter, with microscopic changes typical of progressive multifocal leucoencephalopathy and intranuclear papovavirus inclusions in oligodendrocytes; and lesions of subacute encephalitis in the periventricular regions with large cells positive by immunostaining for CMV. Diffuse myelin loss was observed in the cerebral white matter. Multinucleated giant cells were numerous in the demyelinated areas, they were also observed in close relationship with papova, CMV and Toxoplasma lesions. Immunostaining of these cells was positive for histiocyte markers and negative with the leucocyte common antigen monoclonal antibody. Some of them contained virus-like particles measuring around 100 nm similar to human immune deficiency virus (HIV) as observed in human brain.

Spongiform encephalopathy in a patient with acquired immune deficiency syndrome (AIDS)

The histological and ultrastructural findings of subacute spongiform encephalopathy (SSE) are described in the cerebral cortex and basal ganglia of a homosexual patient who died with acquired immune deficiency syndrome (AIDS). It is suggested that SSE, beside the diffuse AIDS leukoencephalopathy, might be another morphological substrate of the AIDS dementia complex.

Impact of the diagnosis of AIDS on hospital care of an infant

Detailed analysis of caretaker response to the first infant newly diagnosed with AIDS at a university hospital was done by review of nursing notes for three periods: before diagnosis of AIDS, after diagnosis, and after psychiatric consultation. Five consultation questions were posed, and the findings on investigation of these questions are discussed. It was found that the percentage of time that PRN medication was given dropped after diagnosis of AIDS but rose above the initial level after the consultation. The number of times per shift the nurse touched the baby (TLCs) was not found to be associated with use of PRN medication; rather it was explained by which nurse was caring for the child. This study focuses on variations in nursing care of one infant to illustrate how variation in caretaker response can amplify the range of perturbations of the infant's behavioral response. It is speculated that caretakers of patients with AIDS may normally have feelings considered unacceptable in medical settings, including fear, blaming the patient, or a wish to avoid the patient. Such feelings are more difficult to tolerate in the care of children or infants and are superimposed upon the familiar stains associated with the care of chronically ill or dying pediatric patients.

Brain pathology induced by infection with the human immunodeficiency virus (HIV). A histological, immunocytochemical, and electron microscopical study of 100 autopsy cases

Neuropathological examination of brain tissue of 100 patients with infection by the human immunodeficiency virus (HIV), including 98 with clinically manifest acquired immune deficiency syndrome (AIDS), revealed distinct multifocal-disseminated and diffuse brain tissue lesions, which can be regarded as HIV-induced brain lesions: multifocal giant cell encephalitis (MGCE; 4) and progressive diffuse leukoencephalopathy (PDL; 25). These lesions were found in 38 brains, and in 17 in absence of infectious, necrotizing or inflammatory changes of other types. In 13 brains, a combination of MGCE with PDL was seen, suggesting a spectrum of HIV-induced brain lesions. MGCE is characterized by perivascular accumulations predominantly of rod cells, monohistiocytes and macrophages, all of which are strongly labeled with a monoclonal antibody to macrophages. Most conspicuous are multinucleated giant cells which are also labeled by anti-macrophage antibody, and which can be regarded as evidence of the local presence of HIV, as confirmed by electron microscopical detection of HIV particles in four MGCE brains, and by immunocytochemical detection of HIV proteins in two MGCE brains. PDL is characterized by a triad: diffuse myelin loss, astroglial proliferation, and infiltration by mono- and multinucleated macrophages. HIV-induced lesions can be morphologically differentiated from histopathological brain lesions known in immunosuppression, including what is called here nodular encephalitis ["subacute encephalitis" of the literature, in most cases attributable to cytomegalovirus (CMV) or toxoplasmosis], by their characteristic histopathology including the hallmark presence of multinucleated giant cells, by direct immunocytochemical and electron microscopical demonstration of HIV in the lesions, and by the absence of opportunistic agents (bacteria, fungi, Toxoplasma, CMV, HSV or papovaviruses). Diffuse poliodystrophy (diffuse proliferation of astroglia with swollen nuclei, occasionally minor neuronal loss and rod cell proliferation) was found in the cerebral cortex and other gray matter in half of all brains, including cases with gyral atrophy, and may be another correlate of HIV damage to the brain. Morphological delineation of HIV-induced brain lesions is a necessary prerequisite for a meaningful clinical definition of HIV-induced cerebral disease.

Nuclear bridges in multinucleated giant cells associated with primary lymphoma of the brain in acquired immune deficiency syndrome (AIDS)

In an autopsied case of a 37-year-old man with acquired immune deficiency syndrome (AIDS), multinucleated giant cell encephalopathy was noted in close proximity to multiple nodules of primary lymphoma of the brain. Some multinucleated giant cells and macrophages contained HTLV-III-like viral particles. Nuclear bridges, thin strands connecting individual nuclei with one another, were observed with both light and electron microscopes within some of the multinucleated giant cells. There were also thin tapering nuclear processes, which were probably part of nuclear bridges. The possibility that the nuclear bridges and processes represent amitotic nuclear division is discussed.

Management of infectious and immunological complications of acquired immunodeficiency syndrome (AIDS). Current and future prospects

AIDS is caused by a newly recognised virus (human immunodeficiency virus; HIV) which induces a profound defect in cellular immune function associated with increased susceptibility to opportunistic infections and certain malignancies. The clinical presentation of HIV ranges from asymptomatic infection to severe immunodeficiency manifesting as severe life-threatening infectious diseases or malignancies. While major research efforts are being directed toward development of vaccine and discovery of effective antiretroviral drugs, clinicians are faced with AIDS patients with multiple and complicated medical problems including opportunistic infections and certain malignancies. Currently, efforts are directed toward early diagnosis, treatment, and prevention of recurrence of these opportunistic infections. The current approaches are reviewed in this article. Major recent developments in AIDS research include the isolation of the HIV on culture and the availability of the antibody test. Aside from vaccine and antiretroviral drugs, other measures that may be of benefit in the treatment of AIDS patients are immunological enhancement and reconstitution. Several studies are underway to evaluate antiviral agents in the treatment of HIV infection. Those undergoing clinical trial include suramin, ribavirin, antimoniotungstate, phosphonoformate and azidothymidine. Immune enhancers that have been used include alpha- and gamma-interferon and interleukin-2. HLA-matched lymphocyte transfusions and bone marrow transplantations have been used alone and in combination to replace the AIDS patient's defective immune system.

Neuropathology of acquired immune deficiency syndrome (AIDS) in 53 autopsy cases with particular emphasis on microglial nodules and multinucleated giant cells

Brains from 53 autopsied acquired immune deficiency syndrome (AIDS) cases were examined with special attention to microglial nodules and multinucleated giant cells, which are two histological features of AIDS encephalopathy. Twenty-four (45%) of the 53 brains had microglial nodules in varying frequency. Four of these had microglial nodules alone and the rest had other pathological changes, such as opportunistic infections, CNS lymphomas, cerebrovascular lesions, and multinucleated giant cells. Eleven (46%) of the 24 brains with microglial nodules were accompanied by cytomegalovirus infection in the brain (one case) or body (five cases), or both (five cases). However, the remaining 54% of the brains had no morphological evidence of cytomegalovirus infection either in the brain or body. Five brains had multinucleated giant cells and microglial nodules. Two of these brains had numerous multinucleated giant cells, especially in the cerebral white matter, where, in one case, a spectrum of forms included mononuclear macrophages, intermediate forms of binuclear and trinuclear cells, and multinucleated giant cells. Images suggesting cell fusion were also observed. Electron microscopic examination of this area revealed many viral particles (80-130 nm in diameter) with rod-like cores, reminiscent of HTLV-III, in the cytoplasm of one cell.

Inflammatory demyelinating peripheral neuropathies associated with human T-cell lymphotropic virus type III infection

Nine patients with inflammatory demyelinating polyneuropathies (IDP) were found to have human T-cell lymphotropic virus type III (HTLV-III) infection. The 8 men, 6 of whom were homosexual, and 1 woman, a former intravenous drug user, presented with progressive weakness. Two had lymphadenopathy but all were otherwise asymptomatic. Six had chronic IDP and 3 had Guillain-Barré syndrome. In addition to an elevated cerebrospinal fluid (CSF) protein level (mean, 193 mg/dl), most patients had cerebrospinal fluid pleocytosis (mean, 23 cells/mm3), a distinctive feature. All had reduced T4:T8 T-cell ratios. Results of nerve conduction studies were characteristic of demyelination. Nerve biopsies revealed intense inflammatory cell infiltrates and macrophage-mediated demyelination. The patients recovered either spontaneously or following treatment with corticosteroids or plasmapheresis. During a mean interval of 20 months after presentation, only 1 patient had developed acquired immune deficiency syndrome. Patients with HTLV-III infection have disordered immune function, and the mechanism of the development of the IDP is likely to be immunopathogenic. As a result of our experience, we suggest that all patients with IDP be tested for evidence of HTLV-III infection. We also found, although in uncontrolled trials, that treatment with either prednisone or plasmapheresis was followed by clinical improvement; since plasmapheresis is not likely to further depress cell-mediated immunity, we suggest that it be the initial therapy.

Varieties of perseveration: a comparison of two taxonomies

Two taxonomies of perseveration have been independently developed by Goldberg and Tucker (1979) and Sandson and Albert (1984). They are in remarkable agreement with respect to phenomenology of perseveration but differ in terms of postulated mechanisms. Sandson and Albert propose a separate mechanism for every type, whereas Goldberg and Tucker propose a unitary mechanism which can operate at different levels of neurocognitive hierarchy thus producing different types of perseveration. The issue of neuroanatomical specificity of perseveration is also addressed. It is proposed that clinical features of prefrontal syndromes need not imply the presence of selective structural or biochemical damage to prefrontal cortex, and that a structurally diffuse CNS disease often masquerades as a selective frontal-lobe disease. The difference between structural and functional definitions of focal brain disease is emphasized.

Longitudinal study of 18 children with perinatal LAV/HTLV III infection: attempt at prognostic evaluation

We performed a longitudinal study (mean follow-up 19.5 months, range 3 to 42 months) in 18 consecutive children with clinical symptoms of LAV/HTLV III infection. Twelve patients were born to mothers infected with LAV/HTLV III, and six were infected by blood products administered during the first weeks of life. Immunologic studies included lymphocyte markers, in vitro responses to mitogens and antigens with corresponding skin tests, and antibody response with isoagglutinins, post-vaccination antibodies, and Candida. A serologic profile of antibody to GP110, P18, and P25 LAV/HTLV III antigens by radioimmunoprecipitation assay was also performed. The antigen-induced proliferative responses were normal in 10 patients who had a stable course, but were profoundly impaired in eight others who died or had poor condition with opportunistic infections. These in vitro measurements were well correlated with antigen skin tests. An abnormal antibody response to antigens, a low level of isoagglutinins, and a peculiar profile of LAV/HTLV III antibodies were also frequently observed in these eight patients. These measurements appear to be of prognostic value because they were noticed soon after onset of clinical symptoms.

Neurological complications and concomitants of AIDS

A survey of the literature of neurological manifestations associated with the acquired immune deficiency syndrome (AIDS) shows a broad disease spectrum affecting approximately one third of the patients in large hospital series. The complications include focal cerebral lesions caused by abscesses, lymphomas, leucoencephalopathy or infarcts as well as encephalitis, meningitis and myelitis. Most opportunistic infections of the central nervous system presumably are caused by toxoplasma gondii, cytomegalovirus and cryptococcus neoformans. One tenth of all patients have neurological disease as their initial symptom of AIDS. The diagnosis should always be considered in patients at risk and in males with an unusual neurological history or with a peculiar CT scan of the brain. Besides the opportunistic complications of AIDS, LAV/HTLV-III itself probably attacks the nervous system and gives rise to concomitant lesions of the long tracts of the spinal cord with ataxia, paresis and spasticity and to subacute encephalopathy and peripheral nerve abnormalities as well.

Octapeptides deduced from the neuropeptide receptor-like pattern of antigen T4 in brain potently inhibit human immunodeficiency virus receptor binding and T-cell infectivity

The differentiation antigen T4, present on the helper/inducer subset of T lymphocytes, is thought to serve as the receptor for the human immunodeficiency virus (HIV). We find that a 60-kDa protein, immunoprecipitable by monoclonal antibody (mAb) OKT4, is present on membranes from human brain as well as human T cells. Furthermore, the radioiodinated HIV envelope glycoprotein [125I-labeled gp120 (125I-gp120)] can be specifically covalently affixed to a molecule present on rat, monkey, and human brain membranes to yield a complex that is indistinguishable from that formed on human T cells. T4 antigen has been studied on unfixed squirrel monkey, rat, and human brain sections by autoradiography using the mAb OKT4. A highly conserved neuroanatomical pattern has been demonstrated, suggesting an analogous organization in these three mammalian brains. Furthermore, the localization of 125I-gp120 receptor binding appears similar to that of T4 and is highly reminiscent of patterns for many previously characterized neuropeptide receptors. A computer-assisted analysis of gp120 suggested that a previously unremarkable octapeptide sequence within the gp120 protein, which we have synthesized and termed "peptide T," may play an important role in HIV attachment. Thus, peptide T and three rationally designed peptide analogs, each with a systematic amino acid substitution, potently inhibit specific 125I-gp120 binding to brain membranes. Additionally, when tested in a viral infectivity assay, these peptides show the same rank order and similar absolute potency to block HIV infection of human T cells. Thus, peptide T may provide a useful pharmacological or immunological basis for the control and treatment of AIDS.

Neuropathology of acquired immunodeficiency syndrome (AIDS). Analysis of 22 Brazilian cases

The neuropathologic study of 22 Brazilian cases of acquired immuno-deficiency syndrome (AIDS) was performed. Thirteen cases (59%) showed neuropathologic lesions. These included infection by Toxoplasma (n = 4), Cryptococcus neoformans (n = 3), viral encephalitis (n = 4), primary lymphomas (n = 2), isolated cerebral infarct (n = 1), and reactive gliosis (n = 1). In 2 cases, primary lymphoma and viral encephalitis were associated. Axonal spheroids in the gracilis and cuneatus nuclei were present in a case of toxoplasmosis. Mammillary bodies lesions consistent with Wernicke's encephalopathy were found in a case of viral encephalitis. In addition, circulatory changes (focal cortical infarcts) were associated lesions in 3 cases. These findings were compared with the main series reported in American and European literature.

The clinical challenges of AIDS and HIV infection

Researchers trying to resolve the questions surrounding the AIDS epidemic may feel like Hercules trying to slay the Hydra: for every head that is cut off, two new ones grow in its place. Doctors have never treated their patients in a social vacuum, but the expectations and anxieties engendered by AIDS are bringing fundamental changes in clinical p-actice. Drugs are being raced from the laboratory bench to the bedside, health care providers are being forced to recognize new types of family constellations, and the general public is being shocked into awareness of the importance of prudent infection control policies. Clinical practitioners have had to deal with the ethical consequences of routine and arcane decisions as never before, knowing that yesterday's experiment or hospital rounds can become tomorrow's lead feature in the news media.

The T4 gene encodes the AIDS virus receptor and is expressed in the immune system and the brain

The isolation of clones encoding the human surface protein T4, and the expression of the T4 gene in new cellular environments, have enabled us to examine the role of this protein in the pathogenesis of AIDS. Our studies support a mechanism of AIDS virus infection that initially involves the specific interaction of the AIDS virus with T4 molecules on the cell surface. This association can be demonstrated on T4+ transformed T and B lymphocytes as well as epithelial cells. Furthermore, the presence of T4 on the surface of all human cells examined is sufficient to render these cells susceptible to AIDS virus infection. Our data suggest that the T4-AIDS virus complex is then internalized by receptor-mediated endocytosis. Finally, we find that the T4 gene is expressed in the brain as well as in lymphoid cells, providing an explanation for the dual neurotropic and lymphotropic character of the AIDS virus. In this manner, a T lymphocyte surface protein important in mediating effector cell-target cell interactions has been exploited by a human retrovirus to specifically target the AIDS virus to populations of T4+ cells.

Primary central nervous system lymphoma in acquired immune deficiency syndrome: a clinical and pathological study

Twenty cases of primary lymphoma of the central nervous system associated with acquired immune deficiency syndrome were seen over a period of four years and were studied clinically and pathologically. Biopsy established the diagnosis in 11 cases, and autopsy confirmed it in 9. Multicentricity was demonstrated in all cases for which there was adequate autopsy material. Both large-cell immunoblastic and small noncleaved lymphomas were seen, and marker studies in 5 patients established that the lymphomas were of B-cell origin. Neurological symptoms and signs, cerebrospinal fluid characteristics, and radiographic appearance were reviewed. The clinical and radiographic picture is nonspecific and histological confirmation is essential for diagnosis. Although the tumor appears to be radiosensitive, prognosis is extremely poor, with an average survival of less than two months.

Acquired immune deficiency syndrome: an overview of central nervous system complications and neuropsychological sequelae

The Acquired Immune Deficiency Syndrome (AIDS) has been associated with a series of central nervous system (CNS) complications, including focal and nonfocal neurological indications. Overall, the most common form of CNS dysfunction is diffuse cerebral atrophy pathologically characterized by neuronal loss, glial nodules, and microfocal demyelination. Consequent neuropsychological deficits present an insidious course initially typified by poor memory and concentration, along with psychomotor retardation and blunted affect which resembles psychological depression. Gradually over several weeks to months, patients exhibit marked global cognitive impairment and can become severely disoriented and delusional. Clinical research relevant to these CNS complications and neuropsychological sequelae are reviewed.

Isolation and sequence of L3T4 complementary DNA clones: expression in T cells and brain

T lymphocytes express on their surface not only a specific receptor for antigen and major histocompatibility complex proteins, but also a number of additional glycoproteins that are thought to play accessory roles in the processes of recognition and signal transduction. L3T4 is one such T-cell surface protein that is expressed on most mouse thymocytes and on mature mouse T cells that recognize class II (Ia) major histocompatibility complex proteins. Such cells are predominantly of the helper/inducer phenotype. In this study, complementary DNA clones encoding L3T4 were isolated and sequenced. The predicted protein sequence shows that L3T4 is a member of the immunoglobulin gene superfamily. It is encoded by a single gene that does not require rearrangement prior to expression. Although the protein has not previously been demonstrated on nonhematopoietic cells, two messenger RNA species specific for L3T4 are found in brain. The minor species comigrates with the L3T4 transcript in T cells, whereas the major species is 1 kilobase smaller.

Primary lymphoma of the central nervous system: a clinicopathologic analysis of 26 cases

We analyzed 26 cases of primary lymphoma of the central nervous system. There were 14 males and 12 females ranging in age from 5-76 years (median age 51 years, mean age 50.2 years). None had received organ transplantation or immunosuppressive therapy. The most common presenting symptoms were headache, mental changes, nausea, vomiting, and convulsions. The main neurological findings were hemiparesis, papilledema, visual field defects, and cranial nerve palsies. The most common finding in the cerebrospinal fluid (CSF) was high protein content; CSF cytology was positive in only one case. Computerized tomography was done in 14 cases; all showed a contrast-enhancing lesion. Angiography generally revealed an avascular mass. The most common location above tentorium was the frontal lobe; in four cases the tumor was infratentorial (cerebellum, 3 cases). In five cases there was diffuse involvement of the brain; all had severe dementia and diagnosis was not made until the autopsy. Histologically, the most common type was diffuse histiocytic or immunoblastic lymphoma according to Rappaport and the Working Formulation classification respectively. Radiation therapy alone in five patients gave a median survival of 17 months. Five patients received radiation and chemotherapy, and median survival was 16 months. Two patients developed ocular lymphoma 8 and 36 months later that was treated by radiation.

Detection of AIDS virus in macrophages in brain tissue from AIDS patients with encephalopathy

One of the common neurological complications in patients with the acquired immune deficiency syndrome (AIDS) is a subacute encephalopathy with progressive dementia. By using the techniques of cocultivation for virus isolation, in situ hybridization, immunocytochemistry, and transmission electron microscopy, the identity of an important cell type that supports replication of the AIDS retrovirus in brain tissue was determined in two affected individuals. These cells were mononucleated and multinucleated macrophages that actively synthesized viral RNA and produced progeny virions in the brains of the patients. Infected brain macrophages may serve as a reservoir for virus and as a vehicle for viral dissemination in the infected host.