The choroid plexus links innate immunity to CSF dysregulation in hydrocephalus.

The choroid plexus (ChP) is the blood-cerebrospinal fluid (CSF) barrier and the primary source of CSF. Acquired hydrocephalus, caused by brain infection or hemorrhage, lacks drug treatments due to obscure pathobiology. Our integrated, multi-omic investigation of post-infectious hydrocephalus (PIH) and post-hemorrhagic hydrocephalus (PHH) models revealed that lipopolysaccharide and blood breakdown products trigger highly similar TLR4-dependent immune responses at the ChP-CSF interface. The resulting CSF "cytokine storm", elicited from peripherally derived and border-associated ChP macrophages, causes increased CSF production from ChP epithelial cells via phospho-activation of the TNF-receptor-associated kinase SPAK, which serves as a regulatory scaffold of a multi-ion transporter protein complex. Genetic or pharmacological immunomodulation prevents PIH and PHH by antagonizing SPAK-dependent CSF hypersecretion. These results reveal the ChP as a dynamic, cellularly heterogeneous tissue with highly regulated immune-secretory capacity, expand our understanding of ChP immune-epithelial cell cross talk, and reframe PIH and PHH as related neuroimmune disorders vulnerable to small molecule pharmacotherapy.

Choroid plexus immune cell response in murine hydrocephalus induced by intraventricular hemorrhage.

BACKGROUND: Intraventricular hemorrhage (IVH) and associated hydrocephalus are significant complications of intracerebral and subarachnoid hemorrhage. Despite proximity to IVH, the immune cell response at the choroid plexus (ChP) has been relatively understudied. This study employs CX3CR-1GFP mice, which marks multiple immune cell populations, and immunohistochemistry to outline that response. METHODS: This study had four parts all examining male adult CX3CR-1GFP mice. Part 1 examined naïve mice. In part 2, mice received an injection 30 µl of autologous blood into right ventricle and were euthanized at 24 h. In part 3, mice underwent intraventricular injection of saline, iron or peroxiredoxin 2 (Prx-2) and were euthanized at 24 h. In part 4, mice received intraventricular iron injection and were treated with either control or clodronate liposomes and were euthanized at 24 h. All mice underwent magnetic resonance imaging to quantify ventricular volume. The ChP immune cell response was examined by combining analysis of GFP(+) immune cells and immunofluorescence staining. RESULTS: IVH and intraventricular iron or Prx-2 injection in CX3CR-1GFP mice all induced ventriculomegaly and activation of ChP immune cells. There were very marked increases in the numbers of ChP epiplexus macrophages, T lymphocytes and neutrophils. Co-injection of clodronate liposomes with iron reduced the ventriculomegaly which was associated with fewer epiplexus and stromal macrophages but not reduced T lymphocytes and neutrophils. CONCLUSION: There is a marked immune cell response at the ChP in IVH involving epiplexus cells, T lymphocytes and neutrophils. The blood components iron and Prx-2 may play a role in eliciting that response. Reduction of ChP macrophages with clodronate liposomes reduced iron-induced ventriculomegaly suggesting that ChP macrophages may be a promising therapeutic target for managing IVH-induced hydrocephalus.

Hydrocephalus Induced by Intraventricular Peroxiredoxin-2: The Role of Macrophages in the Choroid Plexus.

The choroid plexus (CP) is the primary source of cerebrospinal fluid in the central nervous system. Recent evidence indicates that inflammatory pathways at the CP may be involved in hydrocephalus development. Peroxiredoxin 2 (Prx2) is a major component of red blood cells. Extracellular Prx2 is proinflammatory, and its release after red blood cell lysis may contribute to hydrocephalus after intraventricular hemorrhage. This study aimed to identify alterations in CP macrophages and dendritic cells following intracerebroventricular Prx2 injection and investigate the relationship between macrophages/dendritic cells and hydrocephalus. There were two parts to this study. In the first part, adult male Sprague-Dawley rats received an intracerebroventricular injection of Prx2 or saline. In the second part, Prx2 was co-injected with clodronate liposomes or control liposomes. All animals were euthanized at 24 h after magnetic resonance imaging. Immunohistochemistry was used to evaluate macrophages in CP, magnetic resonance imaging to quantify hydrocephalus, and histology to assess ventricular wall damage. The intracerebroventricular injection of Prx2 not only increased the OX-6 positive cells, but it also altered their location in the CP and immunophenotype. Co-injecting clodronate liposomes with Prx2 decreased the number of macrophages and simultaneously attenuated Prx2-induced hydrocephalus and ventricular wall damage. These results suggest that CP macrophages play an essential role in CP inflammation-induced hydrocephalus. These macrophages may be a potential therapeutic target in post-hemorrhagic hydrocephalus.

Eosinophil activation in the cerebrospinal fluid of children with shunt obstruction.

OBJECTIVE: To determine if eosinophils are activated to release the cationic proteins, eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) in shunt obstruction, and to find out if these proteins are associated with ventriculoperitoneal shunt failure. PATIENTS AND METHODS: This was a prospective observational study carried out in a 20-bed tertiary pediatric intensive care unit. Patients studied were children aged 0-18 years with suspected ventriculoperitoneal shunt malfunction requiring shunt revision. No interventions were performed. Cerebrospinal fluid (CSF) was analyzed for cell count and EDN and ECP concentrations. Patients were prospectively followed for 6 months to evaluate shunt failure. RESULTS: In a 2-month period, 56 shunt revisions were performed on 56 children. Three children had culture-proven infection. Eosinophilia, defined as ≥ 5% eosinophils in the CSF, was present in 9 out of 53 children (17%). The 3 patients with infection did not have eosinophilia and were excluded from further analysis. Patients with CSF eosinophilia had higher concentrations of ECP (1.38 ± 0.66 vs. 0.41 ± 0.15 ng/ml; p = 0.013) and EDN (16.94 ± 5.83 vs. 4.69 ± 1.33 ng/ml; p = 0.011). Patients with CSF eosinophilia did not have more ventriculoperitoneal shunt revisions within 6 months (6 of 9) compared to those who did not have eosinophilia (21 of 44; p = 0.50). However, patients with higher levels of ECP in the CSF required more shunt revisions within 6 months of their surgeries (p < 0.05). CONCLUSIONS: In patients with malfunctioning ventriculoperitoneal shunts, CSF eosinophils are activated and release ECP and EDN. The presence of ECP is associated with a shorter shunt life.

Intracranial Fungal Infection After Solid-Organ Transplant.

Neurologic complications after solid-organ transplant reveal a great spectrum of pathologies. Intracranial hemorrhages, cerebral ischemic lesions, infarctions, lymphoproliferative disorders, and infections, including aspergillosis, have been observed after liver transplant. Fungi constitute nearly 5% of all central nervous system infections, mainly occurring in immunocompromised patients. The most common causative agent is Aspergillus species. It presents either as maxillary sinusitis or pulmonary infection. Brain involvement of Aspergillus carries a high rate of mortality. Aspergillosis presents in the forms of meningitis, mycotic aneurysms, infarctions, and mass lesions. Aspergillosis does not have a specific radiologic appearance. Parenchymal aspergillosis has heterogenous signal intensity (hypointense on T1-weighted and hyperintense on T2-weighted images). Here, we present 3 patients who underwent solid-organ transplant and developed central nervous system aspergillosis. Different modalities of neurosurgical intervention were performed in combination with chemotherapy as part of their fungal therapy.

Effect of shunt catheter on the systemic immune response: evaluation of neutrophil count, function, and rate of chemotaxis.

OBJECT: The localized impairment of the host defense mechanism due to the presence of a shunt apparatus has been suggested as a risk factor for shunt infection. The purpose of this study was to evaluate the probable systemic effect of a shunt catheter on neutrophil phagocytosis and chemotaxis in vivo. METHODS: Twenty-four children with hydrocephalus who were referred to the Children's Hospital Medical Center in Tehran for ventriculoperitoneal shunt placement were included in this study. Neutrophil count, chemotaxis, and nitroblue tetrazolium (NBT) tests were performed before and 2 months after the operation. In comparing the preoperative neutrophil count, NBT percentage, and chemotaxis (with and without the addition of a chemoattractant factor) with these same factors postoperatively, the authors found no statistically significant differences. In four children, shunt infections developed during the follow-up period. There were no significant differences between the aforementioned parameters in children with infected shunts and those with uninfected shunts. CONCLUSIONS: The results of this study do not support the idea of systemic impairment of neutrophils after shunt insertion. Further studies with more specific methods are required to elaborate on this issue.

Congenital posthemorrhagic hydrocephalus: a case of fetomaternal alloimmune thrombocytopenia.

Fetal/neonatal alloimmune thrombocytopenia (NAIT) results from fetomaternal mismatch for human platelet alloantigens leading to antibody-mediated destruction of fetal platelets. This is one of the most common causes of severe thrombocytopenia in the newborn with an incidence of 1/800-1,000. In the most severe cases, NAIT may result in intracranial hemorrhage and may lead to death or neurologic sequelae. We report a case of fetal hydrocephalus caused by NAIT and discuss the importance of making an accurate prenatal diagnosis to improve the management of the current pregnancy and the outcome of subsequent pregnancies. Screening of female siblings of affected cases is recommended in order to detect at-risk individuals.

Hydrocephalus and arthrogryposis in an immunocompetent mouse model of ZIKA teratogeny: A developmental study.

The teratogenic mechanisms triggered by ZIKV are still obscure due to the lack of a suitable animal model. Here we present a mouse model of developmental disruption induced by ZIKV hematogenic infection. The model utilizes immunocompetent animals from wild-type FVB/NJ and C57BL/6J strains, providing a better analogy to the human condition than approaches involving immunodeficient, genetically modified animals, or direct ZIKV injection into the brain. When injected via the jugular vein into the blood of pregnant females harboring conceptuses from early gastrulation to organogenesis stages, akin to the human second and fifth week of pregnancy, ZIKV infects maternal tissues, placentas and embryos/fetuses. Early exposure to ZIKV at developmental day 5 (second week in humans) produced complex manifestations of anterior and posterior dysraphia and hydrocephalus, as well as severe malformations and delayed development in 10.5 days post-coitum (dpc) embryos. Exposure to the virus at 7.5-9.5 dpc induces intra-amniotic hemorrhage, widespread edema, and vascular rarefaction, often prominent in the cephalic region. At these stages, most affected embryos/fetuses displayed gross malformations and/or intrauterine growth restriction (IUGR), rather than isolated microcephaly. Disrupted conceptuses failed to achieve normal developmental landmarks and died in utero. Importantly, this is the only model so far to display dysraphia and hydrocephalus, the harbinger of microcephaly in humans, as well as arthrogryposis, a set of abnormal joint postures observed in the human setting. Late exposure to ZIKV at 12.5 dpc failed to produce noticeable malformations. We have thus characterized a developmental window of opportunity for ZIKV-induced teratogenesis encompassing early gastrulation, neurulation and early organogenesis stages. This should not, however, be interpreted as evidence for any safe developmental windows for ZIKV exposure. Late developmental abnormalities correlated with damage to the placenta, particularly to the labyrinthine layer, suggesting that circulatory changes are integral to the altered phenotypes.

Inflammation-dependent cerebrospinal fluid hypersecretion by the choroid plexus epithelium in posthemorrhagic hydrocephalus.

The choroid plexus epithelium (CPE) secretes higher volumes of fluid (cerebrospinal fluid, CSF) than any other epithelium and simultaneously functions as the blood-CSF barrier to gate immune cell entry into the central nervous system. Posthemorrhagic hydrocephalus (PHH), an expansion of the cerebral ventricles due to CSF accumulation following intraventricular hemorrhage (IVH), is a common disease usually treated by suboptimal CSF shunting techniques. PHH is classically attributed to primary impairments in CSF reabsorption, but little experimental evidence supports this concept. In contrast, the potential contribution of CSF secretion to PHH has received little attention. In a rat model of PHH, we demonstrate that IVH causes a Toll-like receptor 4 (TLR4)- and NF-κB-dependent inflammatory response in the CPE that is associated with a ∼3-fold increase in bumetanide-sensitive CSF secretion. IVH-induced hypersecretion of CSF is mediated by TLR4-dependent activation of the Ste20-type stress kinase SPAK, which binds, phosphorylates, and stimulates the NKCC1 co-transporter at the CPE apical membrane. Genetic depletion of TLR4 or SPAK normalizes hyperactive CSF secretion rates and reduces PHH symptoms, as does treatment with drugs that antagonize TLR4-NF-κB signaling or the SPAK-NKCC1 co-transporter complex. These data uncover a previously unrecognized contribution of CSF hypersecretion to the pathogenesis of PHH, demonstrate a new role for TLRs in regulation of the internal brain milieu, and identify a kinase-regulated mechanism of CSF secretion that could be targeted by repurposed US Food and Drug Administration (FDA)-approved drugs to treat hydrocephalus.

Soluble Toll-Like Receptors 2 and 4 in Cerebrospinal Fluid of Patients with Acute Hydrocephalus following Aneurysmal Subarachnoid Haemorrhage.

BACKGROUND: Toll-like receptor (TLR) signalling begins early in subarachnoid haemorrhage (SAH), and plays a key role in inflammation following cerebral aneurysm rupture. Available studies suggest significance of endogenous first-line blockers of a TLR pathway-soluble TLR2 and 4. METHODS: Eighteen patients with SAH and acute hydrocephalus underwent endovascular coiling and ventriculostomy; sTLR2 and 4 levels were assayed in cerebrospinal fluid (CSF) collected on post-SAH days 0-3, 5, and 10-12. Release kinetics were defined. CSF levels of sTLR2 and 4 were compared with a control group and correlated with the clinical status on admission, the findings on imaging, the degree of systemic inflammation and the outcome following treatment. RESULTS: None of study group showed detectable levels of sTLR2 and 4 on post-SAH day 0-3. 13 patients showed increased levels in subsequent samples. In five SAH patients sTLR2 and 4 levels remained undetectable; no distinctive features of this group were found. On post-SAH day 5 the strongest correlation was found between sTLR2 level and haemoglobin level on admission (cc = -0.498, P = 0.037). On post-SAH day 10-12 the strongest correlation was revealed between sTLR2 and treatment outcome (cc = -0.501, P = 0.076). Remaining correlations with treatment outcome, status at admission, imaging findings and inflammatory markers on post-SAH day 5 and 10-12 were negligible or low (-0.5 ≤ cc ≤ 0.5). CONCLUSIONS: In the majority of cases, rupture of a cerebral aneurysm leads to delayed release of soluble TLR forms into CSF. sTLR2 and 4 seem to have minor role in human post-SAH inflammation due to delayed release kinetics and low levels of these protein.

Increased intracranial pressure induces a rapid systemic interleukin-10 release through activation of the sympathetic nervous system.

There is a bi-directional communication between the immune and central nervous system. In this context, it is known that patients with traumatic brain injury suffered from systemic immunodepression and an increased risk to develop infectious complications. We investigated the role of an increased intracranial pressure (ICP) and sympathetic activation on systemic immune changes. A sustained increase in ICP was achieved by inflation of a subdural balloon. At different time points, plasma levels of the anti-inflammatory cytokine, interleukin (IL)-10, were measured. Furthermore, the effect of a sympathetic blockade by co-administration of the beta2-adreoreceptor antagonist, propranolol, was evaluated. Finally, we examined the impact of epinephrine infusion on blood IL-10 levels. We showed that an increase in ICP with activation of the sympathetic nervous system was able to induce systemic release of IL-10. This effect was blocked by administration of the beta2-adreoreceptor antagonist. Furthermore, epinephrine infusion directly induced systemic release of IL-10. Our data suggested that sympathetic activation with release of epinephrine may induce systemic immunodepression with risk of infectious complications in brain-injured patients.

Hydrocephalus produced by the 6/94 virus; A parainfluenza type 1 isolate from multiple sclerosis brain tissue.

The 6/94 virus, parainfluenza type 1 isolate from multiple sclerosis brain tissue, produced hydrocephalus in newborn Syrian hamsters. All animals developed clinical disease and died within a week. Ependymal cells lining the aqueduct of Sylvius became necrotic and fused, resulting in obstructive hydrocephalus. The 6/94 virus antigen was seen in ependyma and meninges. Paramyxovirus nucleocapsids were seen within cytoplasm of ependymal cells. Virus was recovered from hamster brains for only two days. Infectious virus could be recovered from brains grown in vitro as explants for 21 days. No evidence of rising hemagglutination-inhibiting antibody was noted for up to one month after infection. Intraperitoneal or subcutaneous injection of 6/94 virus did not produce hydrocephalus. HA2 virus and the temperature sensitive mutant of HA2 virus failed to produce hydrocephalus, while Sendai virus caused lesions similar to those of 6/94 virus.

Coxsackievirus group B antibodies in the ventricular fluid of infants with severe anatomic defects in the central nervous system.

Ventricular fluids from four of 28 newborn infants who were initially seen with severe congenital anatomic defects in the central nervous system contained neutralizing antibody to at least one serotype of coxsackieviruses group B. Two of the four infants with anti-coxsackieviruses group B antibody in the ventricular fluid did not have a detectable level of the same antibody(ies) in their serum. The ventricular fluid of one of the infants had immunoglobulin M neutralizing antibody directed against coxsackievirus B6. Of 11 mother-infant pairs that had neutralizing antibody to coxsackieviruses group B in both sera, nearly half had antibodies directed against more than one serotype. These data suggest the possibility of an association between congenital infections with coxsackieviruses group B and rare severe CNS defects.

HLA-class II genes modify outcome of Toxoplasma gondii infection.

Associations between Human Leukocyte Antigen (HLA) (i.e. human major histocompatibility complex [MHC]) genes and susceptibility to infections and inflammatory processes have been described, but causal relationships have not been proven. We characterized effects of HLA-DQ alleles on outcome of congenital toxoplasma infection and found that among Caucasians, the DQ3 gene frequency was significantly higher in infected infants with hydrocephalus (0.783) than infected infants without hydrocephalus (0.444) or published normal controls (0.487). We then developed a novel animal model to definitively determine the effect of these HLA DQ molecules on the severity of toxoplasmosis. Human MHC-Class II transgenes reduced parasite burden and necrosis in brains of mice infected with Toxoplasma gondii. Consistent with the observed association between DQ3 and hydrocephalus in human infants, in the murine model the DQ3(DQ8; DQB1*0302) gene protected less than DQ1 (DQ6; DQB1*0601). Our findings definitively prove a cause and effect relationship between human MHC genes and resistance to infection, provide novel means to characterise human immune responses that are protective or pathogenic in infections, and are important for vaccine development.

Immune reactions associated with silicone-based ventriculo-peritoneal shunt malfunctions in children.

The implantation of ventriculo-peritoneal (VP) shunting systems is the most commonly performed neurological procedure in children with hydrocephalus. Although the overall complication risk is low, the cumulative risk of shunt failure is high and unfortunately results in a high prevalence of revision surgeries. In this study, we explored the concept that some pediatric patients may develop an immune response to either the proteins attached to the silicone implant surface or to the biomaterial itself, and that this reaction may contribute to VP shunt failure in some individuals. The data displays that the sterile shunt malfunction group had a higher rate of protein deposition and increased levels of autoantibodies to the extracted surface proteins as compared to individuals with functioning shunting systems. The precise nature of the shunt-bound proteins that serve as antigens in this experiment have not yet been determined. The data also indicated that some individuals develop antibodies to polymeric substances that cross-react with partially polymerized acrylamide. The detection of significant amounts of shunt-bound protein, antibody responses to these proteins and to polymeric substances suggest that an immunological response to these proteins may play a role in the mechanism behind sterile shunt malfunctions.

Immunoglobulins in certain CNS disorders: a study of CSF Ig classes G, A, M, D, and E concentrations.

Concentrations of cerebrospinal fluid (CSF) Ig classes G, A, M, D, and E have been reported in various neurologic disorders, viz, aseptic meningitis, multiple sclerosis, benign tumor, malignant tumor, and hydrocephalus. In aseptic meningitis, IgG and IgM were found to be either normal or elevated, whereas concentrations of IgA, IgD, and IgE were normal. Multiple sclerosis patients had IgG, IgA, and IgM, either normal or elevated, but IgD and IgE were on the lower end of the normal. Malignant tumor patients had elevated concentrations of IgG, IgA, IgM, and IgE, but their IgD was on the lower end of the normal. In benign tumor population IgA and IgE, and in hydrocephalus IgG and IgA, were found to be elevated in most of the patients. On statistical analysis, significant differences were observed between the means of the normal group and that of the patients' group for all the five immunoglobulins. By linear regression, a statistical relationship was observed between IgA - IgG, IgM - IgG, IgA - IgM and IgA + IgM - IgG in these neurologic disorders.

Differences between ventricular and lumbar cerebrospinal fluid in hydrocephalus secondary to cysticercosis.

We studied ventricular and lumbar cerebrospinal fluid (CSF) in 16 patients with hydrocephalus secondary to meningeal cysticercosis, and samples were taken at the time of the surgical implantation of a ventricular shunt. All lumbar CSF samples revealed raised cell counts (mean, 72 +/- 28/mm3) and protein counts (mean, 78 +/- 12 mg/dl), as well as positive immune reactions to cysticerci antigens. In contrast, 50% of the ventricular CSF samples exhibited cell and protein counts within normal limits and five showed negative immune reactions to cysticerci antigens. Ample differences between ventricular and lumbar CSF were also observed in the contents of glucose and immunoglobulins G, A, and M. The biochemical and immunological composition of the CSF varied greatly along the cerebrospinal axis in patients with chronic arachnoiditis caused by cysticercosis. Our findings further support the premise of the subarachnoid space as an immunologically active substratum and provide information to explain the frequent occlusion of ventricular shunts in patients with hydrocephalus secondary to inflammatory disorders of the subarachnoid space.

Spatial and temporal expression of P-glycoprotein in the congenitally hydrocephalic HTX rat brain.

The purpose of the present study is to examine spatial and temporal expression of P-glycoprotein in the brain of congenitally hydrocephalic HTX rats. P-glycoprotein has been reported not only as a drug efflux pump but also one of the factors that restricts brain edema. We examined the rat brain from postnatal day 1 to 60 using light and electron microscopy, immunohistochemistry, Western immunoblot and reverse transcriptase-polymerase chain reaction (RT-PCR) methods with monoclonal antibody specific for P-glycoprotein. Immunohistochemically, the positive anti-P-glycoprotein reactivity was found in capillaries of the normal control rat cerebrum. In the hydrocephalic HTX rat brains, it was also found in the capillaries, but only very weak to no reactivity was found in the capillaries of the spongy changes and cystic wall in the subcortical and lateral periventricular white matter. Immunoelectron microscopically, the reaction product was found exclusively on the luminal surface of the capillary endothelium in control rats. A tracer study with intracardiac perfusion of lanthanum chloride showed that lanthanum penetrated the tight junctions and passed through the intercellular space. In the Western immunoblot analysis, P-glycoprotein of 170 kDa was detected clearly in most normal control rat brains but it was not found in the hydrocephalic HTX rat brains. Moreover, mdr1 P-glycoprotein gene expression in the subcortical white matter was examined by RT-PCR. It was detected in all normal control rat brains, but not found in the hydrocephalic HTX rat brains. The results suggested that the absence of P-glycoprotein expression in the capillaries of deep subcortical and lateral periventricular white matter of hydrocephalic HTX rats led to a deficiency of the blood-brain barrier and might be related to vasogenic edema and to the formation of the spongy changes and cystic cavities.

Antibody to lymphocytic choriomeningitis virus in children with congenital hydrocephalus.

Antibody to lymphocytic choriomeningitis (LCM) virus was found by the indirect immunofluorescence (IF) technique in high titres in 9 out of 28 children with congenital hydrocephalus and in moderate titres in 6 mothers of these seropositive children. It is suggested that LCM virus or a closely related virus infecting the foetus in utero may play a role in the aetiopathogenesis of some cases of congenital hydrocephalus.

Cytokine expression in patients with treated congenital hydrocephalus: a preliminary report of five patients.

BACKGROUND: Previous studies have described the elaboration of cytokines in experimental models of congenital hydrocephalus using rats or mice. However, there have been no reports of similar studies in humans. OBJECTIVE: To determine the cytokine expression pattern in the cerebrospinal fluid (CSF) of patients with treated congenital hydrocephalus. DESIGN: A prospective study. SETTING: Wentworth Hospital, Durban, South Africa. SUBJECTS: Five patients (three infants and two older patients) with congenital hydrocephalus treated by means of a ventriculoperitoneal shunt. INTERVENTIONS: Immunophenotyping of peripheral blood was performed on a flow cytometer. The isolation, in-vitro stimulation of peripheral blood and CSF mononuclear cells, and intracellular cytokine determination by flow cytometry were performed. MAIN OUTCOME MEASURES: Peripheral blood and CSF cytokine measurements. RESULTS: Although not statistically significant, all measured mean cytokine levels in the peripheral blood of the infant group were consistently higher than that of the adult group. CSF cytokine levels in both groups were similar and unremarkable. CONCLUSION: No clear pattern of CSF cytokine elaboration, either type-1 (T helper 1) (Th1) or Type-2 (T helper 2) (Th2), could be demonstrated in either of the groups. The significance of higher peripheral blood cytokine levels in the infants is unclear, but may be age-related, and is not apparent in the CSF.