Identification of direct connections between the dura and the brain.

The arachnoid barrier delineates the border between the central nervous system and dura mater. Although the arachnoid barrier creates a partition, communication between the central nervous system and the dura mater is crucial for waste clearance and immune surveillance1,2. How the arachnoid barrier balances separation and communication is poorly understood. Here, using transcriptomic data, we developed transgenic mice to examine specific anatomical structures that function as routes across the arachnoid barrier. Bridging veins create discontinuities where they cross the arachnoid barrier, forming structures that we termed arachnoid cuff exit (ACE) points. The openings that ACE points create allow the exchange of fluids and molecules between the subarachnoid space and the dura, enabling the drainage of cerebrospinal fluid and limited entry of molecules from the dura to the subarachnoid space. In healthy human volunteers, magnetic resonance imaging tracers transit along bridging veins in a similar manner to access the subarachnoid space. Notably, in neuroinflammatory conditions such as experimental autoimmune encephalomyelitis, ACE points also enable cellular trafficking, representing a route for immune cells to directly enter the subarachnoid space from the dura mater. Collectively, our results indicate that ACE points are a critical part of the anatomy of neuroimmune communication in both mice and humans that link the central nervous system with the dura and its immunological diversity and waste clearance systems.

Localizing central nervous system immune surveillance: meningeal antigen-presenting cells activate T cells during experimental autoimmune encephalomyelitis.

OBJECTIVE: The onset of neurological signs in experimental autoimmune encephalomyelitis is tightly associated with infiltration and reactivation of T cells in the central nervous system. The anatomic localization of the initial T cell-antigen-presenting cell (APC) interactions leading to reactivation of T cells in the central nervous system is, however, still unclear. We hypothesized that activated CD4(+) T cells gain direct access to the subarachnoid space and become reactivated on encounter with cognate antigen in this compartment. METHODS: C57Bl/6 mice were immunized with MOG35-55, and interactions between CD4(+) T cells and major histocompatibility class II+ APCs in the subarachnoid space were investigated using flow cytometry, confocal microscopy of leptomeningeal whole-mount preparations, time-lapse microscopy of leptomeningeal explants, and in vitro proliferation assays. RESULTS: CD4(+) T cells, polarized to produce Th1/Th17 cytokines, accumulated in the subarachnoid space early during the course of experimental autoimmune encephalomyelitis, before CD4(+) T cells were detected in the spinal cord parenchyma. At this time point, leptomeningeal but not parenchymal CD4(+) T cells incorporated bromodeoxyuridine, indicating local proliferation of CD4(+) T cells in the subarachnoid space. Time-lapse microscopy indicated that these CD4(+) T cells actively scanned the tissue and interacted with local major histocompatibility class II+ APCs, resulting in long-lasting interactions between CD4(+) T cells and major histocompatibility class II+ APCs, suggestive of immunological synapses. INTERPRETATION: These results support the concept that immune surveillance of the central nervous system involves the subarachnoid space and indicate that the leptomeninges play an important role in experimental autoimmune encephalomyelitis initiation.

Population Screening for Urine Antigens to Detect Asymptomatic Subarachnoid Neurocysticercosis: A Pilot Study in Northern Peru.

Subarachnoid neurocysticercosis (SANCC) is a severe and progressive brain infection with Taenia solium. We performed a pilot study of noninvasive screening for SANCC in two endemic villages in northern Peru using a urine antigen screen followed by brain magnetic resonance imaging for participants with elevated levels of antigen. Among the 978 participants screened, we identified eight individuals with SANCC, many of whom were asymptomatic. This represents a minimum prevalence of 0.8% of SANCC, a level higher than expected based on prior studies, and a positive predictive value of 62% for our novel urine screening test. Future studies should confirm whether early detection and management improve clinical outcomes.

B cells and multiple sclerosis.

Clonal expansion of B cells and the production of oligoclonal IgG in the brain and cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS) have long been interpreted as circumstantial evidence of the immune-mediated pathogenesis of the disease and suggest a possible infectious cause. Extensive work on intrathecally produced antibodies has not yet clarified whether they are pathogenetically relevant. Irrespective of antibody specificity, however, the processes of antibody synthesis in the CNS of patients with MS are becoming increasingly clear. Likewise, targeting B cells might be therapeutically relevant in MS and other autoimmune diseases that are deemed to be driven predominantly by T cells. Accumulating evidence indicates that in MS, similar to rheumatoid arthritis, B cells aggregate into lymphoid-like structures in the target organ. The process of aggregation is mediated through the expression of lymphoid-homing chemokines. In the brain of a patient with MS, ectopic B-cell follicles preferentially adjoin the pial membrane within the subarachnoid space. Recent findings indicate that substantial numbers of B cells that are infected with Epstein-Barr virus (EBV) accumulate in these intrameningeal follicles and in white matter lesions and are probably the target of a cytotoxic immune response. These findings, which await confirmation, could be an explanation for the continuous B-cell and T-cell activation in MS, but leave open concerns about the possible pathogenicity of autoantibodies. Going beyond the antimyelin-antibody dogma, the above data warrant further work on various B-cell-related mechanisms, including investigation of B-cell effector and regulatory functions, definition of the consistency of CNS colonisation by Epstein-Barr virus-infected B cells, and understanding of the mechanisms that underlie the formation and persistence of tertiary lymphoid tissues in patients with MS and other chronic autoimmune diseases (ectopic follicle syndromes). This work will stimulate new and unconventional ways of reasoning about MS pathogenesis.

Intrathecal anti-alphaB-crystallin IgG antibody responses: potential inflammatory markers in Guillain-Barré syndrome.

OBJECTIVE: alphaB-crystallin (alphaBC), a small stress protein with cytoprotective and anti-apoptotic functions, is a potent antigen in autoimmune demyelinating diseases. To address the role of alphaBC in Guillain-Barré syndrome (GBS) we analyzed humoral responses against alphaBC in relation to clinical, electrophysiological and CSF features in GBS. METHODS: Anti-alphaBC-IgG antibodies were measured in serum and cerebrospinal fluid (CSF) of patients with GBS (n = 41), infectious inflammatory neurological diseases (n = 21), multiple sclerosis (n = 42), and other, non-inflammatory neurological disorders (n = 40) by ELISA using human recombinant alphaBC. Expression of alphaBC was immunohistochemically analyzed in postmortem peripheral nerve tissue of GBS and controls without neuropathy. RESULTS: Serum alphaBC-IgG antibody levels did not differ between disease groups, whereas alphaBC-IgG antibodies in CSF were increased in GBS and infectious inflammatory neurological diseases. Calculation of an antigen specific alphaBC-IgG index (alphaBC-Ig-G(CSF) x total IgG(CSF))/(alphaBC-IgG(Serum) x total IgG(Serum)) revealed significantly elevated values in patients with GBS compared to other disease groups (p < 0.001). alphaBC-IgG indices exceeding a cut off value > 0.8 had an 85 % specificity and a 76 % sensitivity for GBS. alphaBC was overexpressed in dorsal root ganglia and spinal roots of autopsy cases with GBS. CONCLUSIONS: We demonstrate increased alphaBC-IgG indices in a high proportion of our GBS patients, which reflect enhanced antigen-specific intrathecal antibody responses against abnormally expressed alphaBC in inflamed peripheral nerve tissue. Elevated alphaBC-IgG indices might therefore serve as markers of PNS inflammation and supplement currently used laboratory tests in the diagnosis of GBS.

Elevated cerebrospinal fluid and serum YKL-40 levels are not associated with symptomatic vasospasm in patients with aneurysmal subarachnoid haemorrhage.

YKL-40 is a newly discovered matrix protein that is thought to be released during the acute stages of inflammation. It has recently been speculated that YKL-40 may serve as a specific serological marker of neutrophil function at the site of tissue inflammation. Our aim was to determine whether the levels of YKL-40 in both the cerebrospinal fluid and sera of 22 patients with aneurysmal subarachnoid haemorrhage were associated with either vasospasm or outcome. The levels were also compared with those of 16 control patients with hydrocephalus. We found that patients with aneurysmal subarachnoid haemorrhage had significantly higher YKL-40 levels in both cerebrospinal fluid and serum than controls. However, elevated YKL-40 levels were not associated with symptomatic vasospasm or 6-month outcome. We show that elevated YKL-40 levels are not correlated with the severity of subarachnoid haemorrhage and cannot be used as a serological marker of inflammation in patients with an aneurysm rupture.

Relation between plasmatic and cerebrospinal fluid oxidative stress biomarkers and intrathecal Ig synthesis in Multiple Sclerosis patients.

The aim of this study was to evaluate if cerebrospinal fluid (CSF) oxidative stress biomarkers were related to plasmatic levels and to intrathecal Ig synthesis in 51 patients with Multiple Sclerosis (MS) or clinically isolated syndrome (CIS). Plasmatic and CSF ferric reducing ability (FRA) showed a significant positive correlation (ρ 0.28, p=0.04), while advanced oxidation protein products (AOPPs) did not. A negative correlation was found between IgG synthesis index and CSF FRA levels. No difference in CSF AOPPs or FRA was observed between patients with and without intrathecal IgM synthesis. Our results indicate that plasmatic and CSF FRA are strictly linked, while CSF oxidative stress biomarkers are not related to intrathecal Ig synthesis.

Acute down-regulation of antibody production following spinal cord injury: role of systemic catecholamines.

We investigated whether antibody production to antigens arising in the subarachnoid space is depressed acutely after spinal cord injury (SCI), and whether such depression is due to abnormal catecholamine levels. To assess antibody responses, ovalbumin (OVA) was injected into the spinal subarachnoid space (i.t.) of rats via an indwelling catheter after SCI at T4 or laminectomy (LAM). Antibody responses tested at days 0, 7, and 14 (d0, d7, d14) postinjury revealed that SCI animals exhibited an antibody response significantly lower than LAM animals on d7, but one that reached control levels by d14. ELISPOT assays indicated that the cervical lymph nodes, known to be innervated by superior cervical ganglia (SCG), processed i.t. OVA. The reduction in antibody production after SCI could not be mimicked with surgical deafferentation of the SCG. However, blockade of beta-adrenergic receptors prior to SCI did reverse the decrease, suggesting an adverse effect of the surge of catecholamines that accompanies the injury. Surgical removal of sympathetic inputs to the cervical lymph nodes prior to SCI failed to reverse the effect on antibody production, suggesting a systemic source of catecholamines. We conclude that antibody responses against i.t. antigens are attenuated acutely after SCI due to the massive release of systemic catecholamines that accompanies SCI.

Scanning electron microscopy of the subarachnoid space in the dog. V. Macrophages challenged by bacillus Calmette-Guerin.

Mongrel dogs were anesthetized intraperitoneally with pentobarbitol. One cc of cerebrospinal fluid was drawn through a needle inserted into the cisterna magna and mixed with 1 cc (4-9 million viable BCG organisms) of freeze-dried bacillus Calmette-Guerin. One minute later this mixture was injected by the same needle into the cisterna magna. At 1 and 12 days postinjection, experimental animals were perfused with buffered aldehydes. Samples of the leptomeninges were post-fixed in OsO4 and routinely prepared for scanning and transmission electron microscopy. Leptomeningeal samples of untreated, control animals were similarly prepared. Scanning and transmission microscopy confirm that free cells resting on the subarachnoid linings and within the subpial connective tissue space of control animals possess the morphology of macrophages (Malloy and Low, '76). Viable BCG in the subarachnoid space produces a 3-fold increase in the free cell population of the leptomeninges in 24 hours and a 10-fold increase in 12 days. These cells tend to form associations varying from loose aggregates to tight clusters. Approximately 80% of these free cells express macrophage morphology, with abundant plasma-lemmal microappendages and cytoplasmic vacuoles. Transmission electron microscopy of the free cell population of BCG-stimulated animals reveals at least two other members of the leukocyte series on the leptomeningeal linings.

T-dependent antigens are more immunogenic in the subarachnoid space than in other sites.

Systemic antibody responses were compared in mice injected with antigens into the subarachnoid space (SAS) and into conventional sites. Introduction of T-dependent antigens into the SAS induced higher systemic antibody responses than injections into any other sites. This applied to both soluble and particulate antigens and was more apparent in secondary than in primary responses. The effect was not observed with a T-independent antigen and not consistently with high doses of sheep red blood cells (SRBC). It was concluded that the subarachnoid space is a highly efficient site for the induction of systemic antibody production, in particular to low amounts of T-dependent antigens.

The subarachnoid space as a site for precursor T cell proliferation and effector T cell selection in experimental autoimmune encephalomyelitis.

To characterize the phenotype of inflammatory cells in the central nervous system (CNS) in experimental autoimmune encephalomyelitis (EAE), Lewis rats were immunized with guinea pig myelin basic protein and frozen sections of the spinal cord with EAE were examined immunohistochemically using a panel of monoclonal antibodies against T cells and adhesion molecules. In addition, double immunostaining was performed with glial and T cells markers to examine the interaction between infiltrating T cells and reactive brain cells during the course of EAE. In the early stage of EAE, inflammatory cells first appeared in the subarachnoid space (SAS) and infiltrated the subpial region. The majority of inflammatory cells in SAS expressed TCR alpha beta and either CD4 or CD8 molecules. However, only CD4+ T cells infiltrated the parenchyma while the majority of CD8+ cells remained in SAS. A similar differential localization of T cells was observed with regard to CD45RC molecules. Inflammatory cells in SAS consisted of both CD45RC+ and CD45RC- population, while those in the parenchyma were largely CD45RC-. With regard to adhesion molecules, the leptomeninges constitutively expressed fibronectin (FN) and intercellular adhesion molecule 1 (ICAM-1). Most SAS inflammatory cells expressed very late activation antigen 4 (VLA-4) and, to lesser extent, lymphocyte function-associated antigen 1 (LFA-1) in the early stage of EAE. On the other hand, parenchymal infiltrating cells expressed LFA-1 more strongly in the peak stage. Double staining for V beta 8.2 TCR and microglia demonstrated an increase in the number of microglia together with morphological changes into rod-shape cells in the vicinity of infiltrating T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of cell types producing RANTES, MIP-1 alpha and MIP-1 beta in rat experimental autoimmune encephalomyelitis by in situ hybridization.

The chemokines RANTES, macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta are members of the beta-family of chemokines and potent chemoattractants for lymphocytes and monocytes. To investigate the factors which regulate lymphocyte traffic in experimental autoimmune encephalomyelitis (EAE), we studied, by in situ hybridization analysis, the kinetics of mRNA expression and the potent cellular sources of RANTES, MIP-1 alpha and MIP-1 beta in the central nervous system (CNS) during the course of EAE. RANTES-positive cells appeared in the subarachnoid space and infiltrated the subpial region at around day 10, increased to a peak at days 12-13 and then decreased following the resolution of the acute phase of EAE, though elevated RANTES message expressions still remained on chronic subclinical stage. Most of RANTES positive cells were identified as T-lymphocytes located mainly around blood vessels, by combined studies of in situ hybridization and immunohistochemistry. The remainder of the RANTES-positive cells were astrocytes and macrophages/microglia. MIP-1 alpha and MIP-1 beta mRNA-positive cells appeared around day 10, increased further on days 12-13 and then gradually decreased. Most of the MIP-1 alpha- and MIP-1 beta-positive mononuclear cells were located around blood vessels. The kinetics of RANTES, MIP-1 alpha and MIP-1 beta expression paralleled those of the recruitment of infiltrating inflammatory cells and disease severity. Our observations support the possibility that chemokine production by T-cells, macrophages and astrocytes lead to the infiltration of inflammatory cells into the CNS parenchyma during the acute phase of EAE.

[Integrity of the blood-brain barrier and intrathecal synthesis of IgG in parenchymatous and subarachnoid cerebral cysticercosis]. / Integridad de la barrera hematoencefálica y síntesis intratecal de IgG en cisticercosis cerebral parenquimatosa y subaracnoidea.

Patients with cerebral cysticercosis (CC) have specific antibodies of the IgG type in blood and cerebrospinal fluid (CSF). In order to determine if the specific antibodies present in the CSF come from blood or synthetized in the subarachnoid space, we studied the integrity of the blood brain barrier (BBB) and the intrathecal synthesis of specific antibodies. We found a ruptured BBB with more frequency and in a higher intensity in patients with CC and hydrocephalus (malignant CC) than in patients with parenchymal CC (benign CC). The patients with malignant CC have a greater number of inflammatory cells, a higher albumin index (serum albumin/CSF albumin), a higher level of protein and a higher titre of specific antibodies in the CSF than those with benign CC. In 15 patients in both groups we could demonstrate intrathecal synthesis of antibodies. We conclude that in CC the specific antibodies are produced intrathecally, and in a lesser amount come from the blood through a ruptured blood-brain barrier.

[Changes in the number of immunocompetant cerebrospinal fluid cells in epileptic patients following air insufflation into the subarachnoid space]. / Ob i zmenenii kolichestva immunokompetentnykh kletok spinnomozgovoi zhidkosti u bol'nykh épilepsiei pri insuffliatsii vozdukha v subarakhnoidal'noe prostranstvo.

In 10 patients with various forms of epilepsy the effect of air insufflation into the subarachnoidal space on the number of immunocompetent cells in the cerebrospinal liquor and the peripheral blood was studied. A sharp rise of the percentage of the T- and B-lymphocytes in the cerebrospinal liquor was noted as a result of the insufflation. Examinations of the blood before the insufflation and in the presence of the pronounced post-insufflation meningeal syndrome did not reveal any distinct regularity. A direct relationship between the liquor immune reaction and the intensity of the post-insufflation meningeal syndrome was noted.

Arachnoid cell involvement in the mechanism of coagulation-initiated inflammation in the subarachnoid space after subarachnoid hemorrhage.

OBJECTIVE: To assess if arachnoid cells have the capability to present antigen and activate T-lymphocytes after stimulation by bloody cerebrospinal fluid (CSF), and to illuminate the mechanism of coagulation-initiated inflammation in the subarachnoid space after subarachnoid hemorrhage (SAH). METHODS: Arachnoid cells were cultured, characterized, and examined by immunofluorescence for the basal expression of human leukocyte antigen-DR (HLA-DR). Expression of HLA-DR, after co-culturing arachnoid cells in vitro with bloody CSF, was investigated by immunofluorescence and flow cytometry (FCM). The variation of arachnoid cells' ultrastructure was observed by transmission electron microscope (TEM). Arachnoid cells were co-cultured with peripheral blood mononuclear cells (PBMCs). The content of soluble interleukin-2 receptor (sIL-2r) in culture medium was detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: (1) Arachnoid cells were successfully cultured for many passages. The immunofluorescent staining was positive for HLA-DR in over 95% of the human arachnoid cells. The punctate HLA-DR was distributed in cytoplasm and not in the karyon. (2) After co-culturing arachnoid cells in vitro with bloody CSF, numerous particles with strong fluorescence appeared in the cytoplasm on Day 6. On Day 8, the quantity of particles and fluorescent intensity were maximal. FCM showed that the percentage of HLA-DR expressing cells was (2.5+/-0.4)% at the first 5 d, increasing to (60.8+/-3.6)% on Day 7. (3) After co-culturing arachnoid cells in vitro with bloody CSF, many lysosome and secondary lysosome particles were present in the cytoplasm. Hyperplasia of rough endoplasmic reticulum and enlarged cysts were observed, with numerous phagocytizing vesicles also observed at the edge of the arachnoid cells. (4) Arachnoid cells stimulated by bloody CSF were co-cultured in vitro with PBMCs. The content of sIL-2r in the culture medium, having been maintained at around 1.30 ng/ml during the first 3 d, had increased by Day 4. The content of sIL-2r peaked 7.53 ng/ml on Day 7 and then reduced gradually. CONCLUSIONS: (1) Basic HLA-DR expression is present in arachnoid cells. (2) After stimulation by bloody CSF, arachnoid cells have the potential to serve as antigen presenting cells (APCs) and the ability to activate T-lymphocytes, indicating that arachnoid cells are involved in the mechanism of coagulation-initiated inflammation in the subarachnoid space after SAH.

Elevated B-cell activating factor BAFF, but not APRIL, correlates with CSF cerebellar autoantibodies in pediatric opsoclonus-myoclonus syndrome.

Childhood opsoclonus-myoclonus syndrome (OMS) occurs idiopathic or, in association with a neuroblastoma, as a paraneoplastic syndrome. Since autoantibodies were identified in some patients, an autoimmune pathogenesis has been suspected. While the newly discovered B-cell activating factors BAFF and APRIL are involved in systemic autoimmune diseases, their association with neuroimmunological diseases is hardly understood. We here investigated the BAFF and APRIL levels in serum and cerebrospinal fluid (CSF) of OMS patients and their correlation with surface-binding autoantibodies. BAFF and APRIL were both determined by ELISA, and autoantibodies to cerebellar granular neurons (CGN) have been investigated by flow cytometry in 17 OMS patients, 16 neuroblastoma (NB) patients, 13 controls and 11 children with inflammatory neurological diseases (IND). BAFF, but no APRIL, was elevated in the CSF of OMS children and IND children. However, in contrast to IND patients, OMS patients did not have a blood-brain-barrier disturbance, indicating that BAFF was produced intrathecally in OMS patients, but not in IND patients. CSF BAFF levels showed a correlation with CSF CGN autoantibodies (r(2)=0.58, p<0.05). These data indicate that an activated B-cell system in the cerebrospinal fluid is involved in the pathogenesis of OMS, and BAFF may be a candidate parameter for the activation of B-cell immune system.

Specific recruitment of regulatory T cells into the CSF in lymphomatous and carcinomatous meningitis.

Whereas regulatory T (Treg) cells play an important role in the prevention of autoimmunity, increasing evidence suggests that their down-regulatory properties negatively affect immune responses directed against tumors. Treg cells selectively express chemokine receptors CCR4 and CCR8, and specific migration occurs following the release of various chemokines. Neoplastic meningitis (NM) resulting from leptomeningeal spread of systemic non-Hodgkin lymphoma (NHL) or carcinoma has a poor prognosis. We hypothesized that Treg-cell accumulation within the subarachnoid space as a result of interfering with tumor immunity may be relevant for survival of neoplastic cells. We collected cerebrospinal fluid (CSF) from 101 patients diagnosed with lymphomatous/carcinomatous NM and various inflammatory diseases (IDs) and noninflammatory neurologic disorders (NIDs). CSF Treg- cell counts were determined by flow cytometry, Treg cell-specific chemokines by enzyme-linked immunosorbent assay (ELISA), and Treg-cell trafficking by chemotaxis assay. Both frequencies of Treg-cell and Treg cell-specific chemotactic activities were significantly elevated in CSF samples of patients with NM. Local Treg-cell accumulation occurred without concomitant rise of conventional T (Tconv) cells, coincided with elevated concentrations of Treg cell-attracting chemokines CCL17 and CCL22 and correlated with numbers of atypical CSF cells. We conclude that Treg cells are specifically recruited into the CSF of patients with NM, suggesting that the presence of Treg cells within the subarachnoid space generates a microenvironment that may favor survival and growth of malignant cells.

Evidence of antibody production in the rat cervical lymph nodes after antigen administration into the cerebrospinal fluid.

We previously showed histologically that, in the rat, the cerebrospinal fluid drains from the subarachnoid space along the olfactory nerves to the nasal lymphatics and empties into the superficial and deep cervical lymph nodes. The present study was performed to investigate whether these lymph nodes play a role in the immune response of the central nervous system. For this purpose, keyhole limpet hemocyanin conjugated with fluorescein isothiocyanate (KLH-FITC) was administered into the subarachnoid space of the rat brain, and the time-kinetics and location of FITC and anti-FITC antibody forming cells in the cervical lymph nodes were studied histologically and immunohistochemically. FITC fluorescence was detected in superficial and deep cervical lymph nodes as well as the subarachnoid space and the nasal mucosa 2 h after FITC-KLH injection into the subarachnoid space. The specific antibody-forming cells first appeared in both the superficial and deep cervical lymph nodes on the 4th day after antigen administration although the reaction was more intense in the deep than in the superficial cervical lymph nodes. These cells were located in the medullary cords of the cervical lymph nodes. The number of antibody forming cells increased thereafter, reached a peak around the day 6, and then declined on day 10. These findings indicate that antigens introduced in the cerebrospinal fluid are drained into the cervical lymph nodes through the nasal lymphatics and initiate the antigen-specific immune response there. Thus, the cervical lymph nodes probably act as a monitoring site for cerebrospinal fluid and play a major role in the central nervous system immune response.

Subarachnoidal and intraventricular human neurocysticercosis: application of an antigen detection assay for the diagnosis and follow-up.

BACKGROUND: Neurocysticercosis (NC) is a parasitic disease of the central nervous system caused by the larval stage of Taenia solium. Although imaging studies are recommended for diagnosis and follow-up of patients, their high cost and restricted availability limit their use. Among various immunological tests, the detection of HP10 antigen in cerebral spinal fluid (CSF) has proved to be a useful tool for the diagnosis of NC in the case of viable but not dead parasites. OBJECTIVES: This study was designed to evaluate the usefulness of the detection of HP10 antigen for the diagnosis and follow-up of NC patients. METHODS: The effectiveness of this HP10 assay was analysed for the CSF of 46 confirmed NC cases (21 men, 25 women) who had been clinically and radiologically described. RESULTS: In 21 of 24 NC patients (87.5%) with viable parasites localized in the SA space at the base of the brain or in the ventricles these were detected by means of the HP10 assay, whilst none of the three patients with viable parasites in the parenchyma or sulci had these detected. Used for the follow-up of patients after cysticidal treatment, it was showed that levels of HP10 dropped significantly only among those patients whose cysticerci were clearly damaged. CONCLUSIONS: HP10 antigen assay is recommended as a support for diagnosis and follow-up in NC patients with viable parasites localized in the SA space at the base of the brain or in the ventricles, thereby potentially reducing the number of imaging studies required.

The role of complement in inflammation during experimental pneumococcal meningitis.

The mechanism whereby an effective bactericidal inflammatory reaction develops in the subarachnoid space is not clearly defined. While normal cerebrospinal fluid is deficient in complement, immunoglobulin and leukocytes, these serum components appear in cerebrospinal fluid (CSF) during the course of bacterial meningitis. Using a rabbit model of pneumococcal meningitis we examined the role of the alternate complement pathway in three early events important to the defense of the subarachnoid space: leukocyte chemotaxis, phagocyte mediated bacterial killing, and clearance of bacterial components from the cerebrospinal fluid space. Rabbits treated with cobra venom factor to deplete complement were inoculated intracisternally with encapsulated (type II or XIX) pneumococci. Following complement depletion, there was a dramatic (at least 100-fold) decrease in the LD50 for these strains. Nevertheless, complement depletion did not affect the magnitude of CSF leucocytosis or the rate of clearance of bacterial particles from CSF. A short delay in the appearance of leukocytes in CSF was found in the absence of complement. The major effect of complement depletion, however, was to diminish the efficiency of leukocyte mediated killing of encapsulated bacteria in the CSF. Although the short delay in the onset of leukocytosis in the complement depleted animals is consistent with a chemotactic role of complement in the normal animal, the quantitatively normal leukocytosis in the complement depleted rabbits clearly indicates that important chemotaxins other than complement function in CSF. Inhibition of leukocytosis by indomethacin and diclofenac suggests that metabolite(s) of the arachidonic acid pathway may perform such a chemotactic role. A major role of complement in the defense of the subarachnoid space appears to be as an opsonin needed for the effective bactericidal activity of leukocytes. It is the lack of this function that best explains the greatly decreased LD50 value of encapsulated pneumococci in the complement depleted animal.