Cytokine and chemokine responses in a cerebral malaria-susceptible or -resistant strain of mice to Plasmodium berghei ANKA infection: early chemokine expression in the brain

A comparative study was carried out on cytokine and chemokine responses in a cerebral malaria (CM)-susceptible or -resistant strain of mice (C57BL/6 or BALB/c respectively) in Plasmodium berghei ANKA infection. C57BL/6 mice died by 10 days after infection when parasitemia was approximately 15-20% with cerebral symptoms, while BALB/c mice survived until week 3 after infection. Although both strains showed T(h)1-skewed responses on day 4 after infection, significantly higher levels of IFN-gamma, tumor necrosis factor (TNF)-alpha and NO were observed during the course of the infection in BALB/c, suggesting that T(h)1 responses are involved in the resistance. Interestingly, in the brain, both strains expressed IFN-inducible protein of 10 kDa (IP-10) and monocyte chemotactic protein (MCP)-1 genes as early as at 24 h post-infection, whereas some differences were observed between both strains thereafter, i.e. enhanced expression of RANTES in C57BL/6, and of IFN-gamma and TNF-alpha in BALB/c respectively. Moreover, the expression of IP-10 and MCP-1 genes in KT-5, an astrocyte cell line, was induced in vitro upon stimulation with a crude antigen of malaria parasites. These results suggest that the direct involvement of brain parenchymal cells takes place in response to plasmodial infection, providing a new aspect to analyze possible mechanisms of CM. This is the first report on the chemokine expression in neuroglial cells in response to malaria infection.     

调节性T细胞修饰前炎症应答对小鼠脑型疟疾发生的影响

为探讨调节性T细胞（Tregs）对伯氏疟原虫感染所致鼠脑型疟发生和感染结局的影响机制,用伯氏疟原虫ANKA株分别感染对照组和抗CD25单克隆抗体注射组C57BL／6小鼠,计数红细胞感染率;感染前和感染后3、5、8天制备脾细胞悬液,流式细胞术检测脾Tregs百分含量;ELISA和Griess方法检测脾细胞培养上清IFN-γ、IL-10和NO水平。结果表明大多数C57BL／6鼠于感染后8—11天死于脑疟,抗CD25单克隆抗体注射组小鼠感染后3～4周死于贫血和过度原虫血症。对照组小鼠脾细胞培养上清IFN-γ、NO、IL—10水平于感染后开始升高,感染后5天达到峰值,感染后8天与感染后5天相比,IFN-γ、NO轻微下降,IL-10显著下降。感染后3、5天,实验组IFN-γ、NO水平显著高于对照组,IL—10水平显著低于对照组。感染后8天,实验组和对照组IFN-γ、NO、IL-10水平得到逆转。这表明Tregs通过修饰前炎症应答影响伯氏疟原虫感染鼠脑型疟发生和感染结局。     

Critical role of IL‐33 receptor ST2 in experimental cerebral malaria development

Cerebral malaria, a severe complication of Plasmodium falciparum infection, can be modeled in murine Plasmodium berghei ANKA (PbA) infection. PbA‐induced experimental cerebral malaria (ECM) is CD8⁺ T‐cell mediated, and influenced by T_H1/T_H2 balance. Here, we show that IL‐33 expression is increased in brain undergoing ECM and we address the role of the IL‐33/ST2 pathway in ECM development. ST2‐deficient mice were resistant to PbA‐induced neuropathology. They survived >20 days with no ECM neurological sign and a preserved cerebral microcirculation, while WT mice succumbed within 10 days with ECM, brain vascular leakage, distinct microvascular pathology obstruction, and hemorrhages. Parasitemia and brain parasite load were similar in ST2‐deficient and WT mice. Protection was accompanied by reduced brain sequestration of activated CD4⁺ T cells and perforin⁺ CD8⁺ T cells. While IFN‐γ and T‐cell‐attracting chemokines CXCL9 and CXCL10 were not affected in the absence of functional ST2 pathway, the local expression of ICAM‐1, CXCR3, and LT‐α, crucial for ECM development, was strongly reduced, and this may explain the diminished pathogenic T‐cell recruitment and resistance to ECM. Therefore, IL‐33 is induced in PbA sporozoite infection, and the pathogenic T‐cell responses with local microvascular pathology are dependent on IL‐33/ST2 signaling, identifying IL‐33 as a new actor in ECM development.     

Role of IL‐10‐producing regulatory B cells in control of cerebral malaria in Plasmodium berghei infected mice

Cerebral malaria (CM) is a neurological syndrome often occurring in severe malaria. Although CM is known as an immunopathology in brain tissue mediated by excessive proinflammatory cytokines, the immunoregulatory mechanism is poorly understood. Here, we investigated the role of IL‐10‐producing regulatory B (Breg) cells in modulating CM development in a murine model of Plasmodium berghei ANKA infection. We observed that blood‐stage P. berghei induced expansion of IL‐10‐producing Breg cells in C57BL/6 mice. Adoptive transfer of IL‐10⁺ Breg cells to P. berghei infected mice significantly reduced the accumulation of NK and CD8⁺ T cells and hemorrhage in brain tissue, and improved the survival of the mice compared with control groups, although parasitemia levels were not altered. Treatment of Breg‐cell recipient mice with anti‐IL‐10 receptor mAb blocked the protective effect of Breg cells. Adoptive transfer of CD4⁺CD25⁺ Treg cells failed to prevent CM in infected mice. Spleen cells from Breg‐cell recipient mice produced increased levels of IL‐10 in vitro. Cell co‐culture showed that purified IL‐10⁺ B cells, but not IL‐10^? B cells, promoted IL‐10 production by CD4⁺ T cells. These results demonstrate that IL‐10‐producing Breg cells may represent an important mechanism for controlling the immunopathology and prevention of CM associated with P. berghei infection.     

昆明小鼠对伯氏疟原虫的易感性和组织病理研究

目的探讨昆明小鼠对伯氏疟原虫（Plasmodium berghei）的易感性及其感染后的组织病理变化。方法 6周龄昆明小鼠腹腔接种1×106个感染伯氏疟原虫的红细胞,观察小鼠的生存时间及临床症状。感染后第2天开始每天采尾静脉血制作薄血膜片,Giemsa染色,计数血虫率。感染后第4天开始经肛门测小鼠体温。小鼠临死时取脑、肺、肝和脾组织,经10%中性福尔马林固定24h以上,脱水、包埋后制成4μm厚石蜡切片,苏木素-伊红染色,显微镜下观察各组织的病理变化。结果昆明小鼠腹腔接种感染伯氏疟原虫后的生存时间为8～21d;小鼠感染后第2天外周血可检出疟原虫,小鼠临死前血虫率达高峰;肉眼观察肝、脾体积增大,颜色变深,显微镜下见大量疟色素沉着,肝实质组织可见少量灶性炎性细胞聚集;脑和肺组织见感染疟原虫红细胞沉积在微血管壁,引起脑血管堵塞、大脑皮层出血灶和肺水肿、肺泡腔内炎性细胞渗出。结论昆明小鼠对伯氏疟原虫易感性较高,脑、肺、肝和脾组织均呈现出典型的疟疾病理特征,可作为研究疟原虫致病机制的动物模型。     

伯氏疟原虫感染早期的根治性治疗对再感染体液免疫应答的影响

为探讨疟疾感染早期根治性治疗对再感染体液免疫应答的影响,用伯氏疟原虫感染DBA/2小鼠,感染后3天进行根治性治疗,并于初次感染后90天再进行感染.通过薄血膜吉姆萨染色法计数红细胞感染率,流式细胞术检测再感染前(0天)和再感染后(1、3、5天)不同时间点脾细胞中活化性B细胞百分率,ELISA检测血清中特异性IgG、IgG...     

伯氏疟原虫感染早期的根治性治疗对再感染细胞免疫应答的影响

目的探讨疟疾感染早期根治性治疗对再感染细胞免疫应答的影响。方法用伯氏疟原虫感染DBA/2小鼠,感染后3d进行根治性治疗,并于初次感染后90d进行再感染。通过吉姆萨薄血膜染色法计数红细胞感染率,流式细胞术检测再感染前（0d）和再感染后（1、3、5d）不同时间点脾T细胞中活化性T细胞百分含量,ELISA检测脾细胞培养上清中IFN-γ、TNF-α、IL-4和IL-10水平。结果同源疟原虫再感染后,根治性治疗小鼠仅出现短暂的低水平虫体血症;再感染后第1～5天活化性T细胞百分率持续升高。IFN-γ于再感染后第1天即出现有意义的升高,第3天达到峰值水平,与此同时,TNF-α和IL-10水平也开始出现有意义的升高,但IL-4的升高出现在再感染后的第5天。结论疟疾感染早期的根治性治疗并不影响宿主在再感染时产生有效的细胞免疫应答,CD4＋Th1应答反应也是抵御疟疾再感染的关键因素之一。     

IgE elevation and IgE anti-malarial antibodies in Plasmodium falciparum malaria: association of high IgE levels with cerebral malaria.

In the course of studying immunoregulation in human Plasmodium falciparum malaria we have investigated IgE levels and IgE anti-plasmodial antibodies in children and adults from areas of high malaria endemicity in both Africa and Asia. On average, 85% of all donors had significantly elevated levels of total IgE. A fraction of the IgE had anti-plasmodial activity as revealed by ELISA with lysates of infected erythrocytes as antigen. Using synthetic peptides representing antigenic regions of two major plasmodial blood stage antigens, IgE antibody concentrations ranged from 5 to 15 ng/ml serum for each of the peptides. On average, the concentrations of the corresponding IgG antibodies were x 500-1000 higher. Immunoblotting of parasite lysates showed that most donors had IgE antibodies against one or several of a restricted number of plasmodial polypeptides, with antibodies against an antigen of mol.wt 45 kD already being present in all donors at an early age. Donors having IgE antibodies to particular antigens also frequently had corresponding IgG4 antibodies, reflecting underlying IL-4-dependent cellular mechanisms controlling formation of these isotypes. As infection with other parasites such as helminths is known to induce IgE elevation, the results do not prove that plasmodial infections were the primary cause of IgE induction. However, the importance of plasmodial infection for IgE elevation was supported by the finding of significantly higher levels of IgE, but not of IgG, in children with cerebral malaria compared with patients with uncomplicated disease.     

Type I interferons contribute to experimental cerebral malaria development in response to sporozoite or blood‐stage Plasmodium berghei ANKA

Cerebral malaria is a severe complication of Plasmodium falciparum infection. Although T‐cell activation and type II IFN‐γ are required for Plasmodium berghei ANKA (PbA)‐induced murine experimental cerebral malaria (ECM), the role of type I IFN‐α/β in ECM development remains unclear. Here, we address the role of the IFN‐α/β pathway in ECM devel‐opment in response to hepatic or blood‐stage PbA infection, using mice deficient for types I or II IFN receptors. While IFN‐γR1^?/? mice were fully resistant, IFNAR1^?/? mice showed delayed and partial protection to ECM after PbA infection. ECM resistance in IFN‐γR1^?/? mice correlated with unaltered cerebral microcirculation and absence of ischemia, while WT and IFNAR1^?/? mice developed distinct microvascular pathologies. ECM resistance appeared to be independent of parasitemia. Instead, key mediators of ECM were attenuated in the absence of IFNAR1, including PbA‐induced brain sequestration of CXCR3⁺‐activated CD8⁺ T cells. This was associated with reduced expression of Granzyme B, IFN‐γ, IL‐12Rβ2, and T‐cell‐attracting chemokines CXCL9 and CXCL10 in IFNAR1^?/? mice, more so in the absence of IFN‐γR1. Therefore, the type I IFN‐α/β receptor pathway contributes to brain T‐cell responses and microvascular pathology, although it is not as essential as IFN‐γ for the development of cerebral malaria upon hepatic or blood‐stage PbA infection.     

T cell response in malaria pathogenesis: selective increase in T cells carrying the TCR V(beta)8 during experimental cerebral malaria.

To characterize the T cells involved in the pathogenesis of cerebral malaria (CM) induced by infection with Plasmodium berghei ANKA clone 1.49L (PbA 1.49L), the occurrence of the disease was assessed in mice lacking T cells of either the alphabeta or gammadelta lineage (TCRalphabeta(-/-) or TCRgammadelta(-/-)). TCRgammadelta(-/-) mice were susceptible to CM, whereas all TCRalphabeta(-/-) mice were resistant, suggesting that T cells of the alphabeta lineage are important in the genesis of CM. The repertoire of TCR V(beta) segment gene expression was examined by flow cytometry in B10.D2 mice, a strain highly susceptible to CM induced by infection with PbA 1.49L. In these mice, CM was associated with an increase of T cells bearing the V(beta)8.1, 2 segments in the peripheral blood lymphocytes. Most V(beta)8.1, 2(+) T cells from peripheral blood lymphocytes of the mice that developed CM belonged to the CD8 subset, and exhibited the CD69(+), CD44(high) and CD62L(low) phenotype surface markers. The link between the increase in V(beta)8.1, 2(+) T cells and the neuropathological consequences of PbA infection was strengthened by the observation that the occurrence of CM was significantly reduced in mice treated with KJ16 antibodies against the V(beta)8.1 and V(beta)8.2 chains, and in mice rendered deficient in V(beta)8.1(+) T cells by a mouse mammary tumor virus superantigen.     

CTLA-4-dependent mechanisms prevent T cell induced-liver pathology during the erythrocyte stage of Plasmodium berghei malaria

During the course of malaria several organs develop pathology. Frequently also signs of hepatocyte damage are found. In the present work we studied the mechanisms leading to liver pathology during the erythrocyte stage of Plasmodium berghei malaria. During infection, mice developed an inflammation of the liver, associated with infiltration of T cells, although only little tissue damage could be observed. Histological analysis revealed the presence of CTL-associated antigen-4 (CTLA-4)-positive T cells in the liver parenchyma. To study the influence of CTLA-4 expression on liver inflammation, mice were treated with an antibody against CTLA-4. Treated mice suffered from a dramatically increased liver pathology. Using cytokine-deficient mice we found that pathology was dependent on the presence of IL-12 and IFN-gamma. To further study the mechanisms that lead to an enhanced pathology, we analyzed cytokine production from liver-derived T cells. In infected mice the frequency of IFN-gamma-producing cells in the liver was low. In contrast, in anti-CTLA-4-treated mice larger numbers of IFN-gamma-producing cells were detectable. Our results indicate that activated T cells during the erythrocyte stage of malaria can induce pathology due to secretion of pro-inflammatory cytokines. Moreover, these results provide evidence that CTLA-4 expression can restrict T cell function in inflamed organs and might therefore prevent pathology.     

Increased eosinophil activity in acute Plasmodium falciparum infection—association with cerebral malaria

To assess the eosinophil response to Plasmodium falciparum infection a cohort of initially parasite-free Ghanaian children was followed for 3 months. Seven of nine children who acquired an asymptomatic P. falciparum infection showed increase in eosinophil counts, while a decrease was found in seven of nine children with symptomatic malaria, and no change was observed in 14 children who remained parasite-free. In a hospital-based study, paediatric patients with cerebral malaria (CM), severe anaemia (SA), or uncomplicated malaria (UM) had uniformly low eosinophil counts during the acute illness followed by eosinophilia 30 days after cure. Plasma levels of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) were measured as indicators of eosinophil activation. In spite of the low eosinophil counts, ECP levels were increased on day 0 and significantly higher in patients with CM (geometric mean (95% confidence interval) 8.5 ng/ml (6.8–10.7 ng/ml)) than in SA (4.7 ng/ml (3.0–7.5 ng/ml)) and UM patients (4.3 ng/ml (3.6–5.3 ng/ml), P < 0.001). A similar pattern was found for EPX. It thus appears that the low eosinophil counts may be due to tissue sequestration and destruction rather than decreased production. The plasma levels of the granule proteins correlated with levels of tumour necrosis factor and soluble IL-2 receptor, implicating inflammatory responses and T cell activation as causes of the eosinophil activation. By contrast, the eosinophil induction did not appear to be part of a Th2-like response. Eosinophil granule proteins may be important in both control of malaria infection and the pathogenesis of severe malaria.     

Acamprosate attenuates the handling induced convulsions during alcohol withdrawal in Swiss Webster mice

In the present study, we examined the effects of acamprosate for its ability to reduce handling induced convulsions (HICs) during alcohol withdrawal. Diazepam was used as a positive control. Swiss Webster male mice received three daily IP injections of alcohol (2.5 g/kg) or alcohol (2.5 g/kg)+methylpyrazole (4-MP) (9 mg/kg). (4-MP, being an alcohol dehydrogenase inhibitor slows down the breakdown of alcohol. 4-MP in combination with alcohol exhibits a dramatic increase in blood alcohol level compared to alcohol alone). Ten hours following the last alcohol injection, the mice were picked up by the tail and examined for their seizure susceptibility (HICs). Diazepam, a benzodiazepine known to reduce seizures during alcohol withdrawal, significantly reduced these HICs at doses of 0.25, 0.5 and 1 mg/kg (p's<0.001). Acamprosate, an anti-relapse compound used clinically in newly abstinent alcoholics, also reduced these HICs at doses of 100, 200 and 300 mg/kg (p's<0.05). This study supports the use of acamprosate during periods of alcohol withdrawal as well as during abstinence.     

Prevention of experimental cerebral malaria by Flt3 ligand during infection with Plasmodium berghei ANKA

Dendritic cells are the most potent antigen-presenting cells, but their roles in blood-stage malaria infection are not fully understood. We examined the effects of Flt3 ligand, a cytokine that induces dendritic cell production, in vivo on the course of infection with Plasmodium berghei ANKA. Mice treated with Flt3 ligand showed preferential expansion of CD8(+) dendritic cells and granulocytes, as well as lower levels of parasitemia, and were protected from the development of lethal experimental cerebral malaria (ECM). Rag2 knockout mice treated with Flt3 ligand also showed inhibition of parasitemia, suggesting that this protection was due, at least in part, to the stimulation of innate immunity. However, it was unlikely that the inhibition of ECM was due simply to the reduction in the level of parasitemia. In the peripheral T cell compartment, CD8(+) T cell levels were markedly increased in Flt3 ligand-treated mice after infection. These CD8(+) T cells expressed CD11c and upregulated CXCR3, while the expression of CD137, CD25, and granzyme B was reduced. In the brain, the number of sequestered CD8(+) T cells was not significantly different for treated versus untreated mice, while the proportion of CD8(+) T cells that produce gamma interferon (IFN-γ) and granzyme B was significantly reduced in treated mice. In addition, sequestration of parasitized red blood cells (RBCs) in the brain was reduced, suggesting that altered CD8(+) T cell activation and reduced sequestration of parasitized RBCs culminated in inhibition of ECM development. These results suggest that the quantitative and qualitative changes in the dendritic cell compartment are important for the pathogenesis of ECM.     

Susceptibility to experimental cerebral malaria induced by Plasmodium berghei ANKA in inbred mouse strains recently derived from wild stock

The neurological syndrome caused by Plasmodium berghei ANKA in rodents partially mimics the human disease. Several rodent models of cerebral malaria (CM) exist for the study of the mechanisms that cause the disease. However, since common laboratory mouse strains have limited gene pools, the role of their phenotypic variations causing CM is restricted. This constitutes an obstacle for efficient genetic analysis relating to the pathogenesis of malaria. Most common laboratory mouse strains are susceptible to CM, and the same major histocompatibility complex (MHC) haplotype may exhibit different levels of susceptibility. We analyzed the influence of the MHC haplotype on overcoming CM by using MHC congenic mice with C57BL/10 and C3H backgrounds. No correlation was found between MHC molecules and the development of CM. New wild-derived mouse strains with wide genetic polymorphisms were then used to find new models of resistance to CM. Six of the twelve strains tested were resistant to CM. For two of them, F(1) progeny and backcrosses performed with the reference strain C57BL/6 showed a high level of heterogeneity in the number and characteristics of the genetic factors associated with resistance to CM.     

Supplementation of CXCL12 (CXCL12) induces homing of CD11c+ dendritic cells to the spleen and enhances control of Plasmodium berghei malaria in BALB/c mice

In malaria, parasitaemia is controlled in the spleen, a multicomponent organ that undergoes changes in its cellular constituents to control the parasite. During this process, dendritic cells (DCs) orchestrate the positioning of effector cells in a timely manner for optimal parasite clearance. We have recently demonstrated that CXCL12 [stromal cell‐derived factor‐1 (CXCL12)] supplementation partially restores the ability to control parasitaemia in Plasmodium berghei‐infected mice. In the present study, we investigated the nature of the DCs involved by flow cytometry and immunohistochemistry of CD11c⁺ cells. Flow cytometry of bone marrow cells showed that infection with P. berghei did not alter the proportion of CD11c⁺ cells present in this haematopoietic compartment, while CXCL12 supplementation of naïve uninfected mice induced only minor increases in the population of CD11c⁺ cells. In the spleen, P. berghei infection alone resulted in an increase in CD11c⁺ cells as compared with naïve animals. Exogenously administered CXCL12 in the absence of infection resulted in a significant expansion of the splenic CD11c⁺ population, and this effect was even more pronounced in infected and supplemented mice. Immunohistochemistry revealed that CD11c⁺ cells infiltrated the perivascular areas and marginal zone of the spleen in infected animals treated with CXCL12, suggesting that this chemokine induces homing of CD11c⁺ dendritic cells to the splenic compartment. Our results show that small amounts of CXCL12 supplementation are effective in recruiting DCs to the spleens of both uninfected and infected mice, suggesting the participation of CXCL12 and CD11c⁺ cells in the establishment of an adequate environment in the spleen for malaria control.     

CXCR3 determines strain susceptibility to murine cerebral malaria by mediating T lymphocyte migration toward IFN-gamma-induced chemokines

Cerebral malaria (CM) results from the binding of infected erythrocytes and leukocytes to brain endothelia. The precise mechanisms underlying lymphocyte recruitment and activation in CM remain unclear. Therefore, the expression of various chemokines was quantified in brains of mice infected with Plasmodium berghei ANKA (PbA). Several chemokines attracting monocytes and activated T-lymphocytes were expressed at high levels. Their expression was almost completely abrogated in IFN-gamma ligand and receptor KO mice, indicating that IFN-gamma is an essential chemokine inducer in vivo. Surprisingly, the expression levels of chemokines, IFN-gamma and also adhesion molecules in the brain were not lower in CM-resistant Balb/c and DBA/2 mice compared to CM-sensitive C57BL/6 and DBA/1 mice, although T lymphocyte sequestration in the brain was significantly less in CM-resistant than in CM-sensitive mice. This difference correlated with a higher up-regulation of the CXC chemokine receptor (CXCR)-3 on splenic T cells and a higher chemotactic response to IFN-gamma-inducible protein-10 (IP-10) in C57BL/6 compared to Balb/c mice. In conclusion, parasite-induced IFN-gamma in the brain results in high local expression levels of specific chemokines for monocytes and lymphocytes. The strain-dependent susceptibility to develop CM is more related to the expression of CXCR3 in circulating leukocytes than to the chemokine expression levels in the brain.     

In vivo studies on the biochemical indices of Plasmodium berghei infected mice treated with Alstonia boonei leaf and root extracts

BackgroundA study on the biochemical indices of albino mice infected with Plasmodium berghei and treated with Alstonia boonei aqueous and ethanolic extracts was undertaken.Methods216 males mice were randomly assigned to six treatment groups each containing six mice for both aqueous and ethanolic extracts experiments. P. berghei NK-65 was inoculated into the mice intraperitoneally and establishment of infection confirmed. Administration of extracts of was done after phytochemical and acute toxicity tests at varying concentrations, for both suppressive and curative tests. Blood samples collected by ocular puncturing were examined for the biochemical indices; ALT, AST, ALP, creatinine and total protein using the standard procedures.ResultsA. boonei extracts suppression of P. berghei in mice was comparable to the standard drug. Significantly higher (p<0.05) recovery of mice treated with A. boonei extracts was observed. The biochemical indices examined all had significantly (p<0.05) increased concentration after 7 days post-infection, except for total protein concentration which had no significant increase or decrease due to A. boonei extracts administration.ConclusionThe antiplasmodial potentials of A. boonei leaf and root extracts were dosage and duration-dependent, and have demonstrated satisfactory normalization of altered biochemical indices due to malaria.     

Human cerebral malaria: characterization of malarial antibodies in cerebrospinal fluid.

Anti-malarial antibodies were quantified in cerebrospinal fluid (CSF) of 17 cases of cerebral malaria, 16 presumptive cases (no demonstrable parasitaemia in peripheral blood but responding to i.v. quinine therapy) of cerebral malaria, and 15 controls. A schizont-enriched Plasmodium knowlesi antigen was used in an ELISA. Anti-malarial antibodies of IgA and IgM isotypes were not detectable in most of the CSF samples analysed, although serum antibody titres were high. However, 88% of CSF from cerebral malaria and 56% of presumptive cerebral malaria cases had significant levels of IgG anti-malarial antibodies in comparison to control CSF. The antibody levels did not correlate with the severity of coma but correlated well with the duration of coma. The CSF malarial antibody titres were independent of degree of parasitaemia. The possible role of CSF anti-malarial antibodies in cerebral malaria in the light of recent demonstrations of intrathecal synthesis of immunoglobulins and deposition of immune complex in cerebral tissues is discussed.