Human bancroftian filariasis - a role for antibodies to parasite carbohydrates

Studies on immune responses to parasites have been undertaken in filariasis with a view to understand protective immunity, pathogenesis of the disease process and mechanisms of immune deviation. However none of the investigations conducted so far on antibody responses have addressed the issue of immunogenicity of filarial carbohydrate antigens in human lymphatic filariasis. In this communication we report details on relative protein and carbohydrate contents of various developmental stages of filarial parasites and antibody responses to filarial proteins (Fil.Pro) and carbohydrates (Fil.Cho) in different clinical spectrum of human bancroftian filariasis. As expected, antibodies of IgM and IgG2 subclass recognized primarily Fil.Cho while IgG4 filarial antibodies recognized exclusively Fil.Pro. Reactivity of IgG3 to Fil.Cho was similar to that of IgG2 while IgG1 more readily recognized Fil.Pro than Fil.Cho. The IgG2 and IgG3 antibodies to Fil.Cho were found to be significantly more in patients with chronic filarial disease and in endemic normals when compared with microfilariae (mf) carriers while IgG4 antibodies to Fil.Pro were significantly more in mf carriers. The dichotomy in reactivity of filarial IgG2, IgG3 and IgG4 was dependent on active filarial infection as indicated by presence of circulating filarial antigen (CFA). Individuals with CFA were found to possess significantly more IgG4 to Fil.Pro than those without CFA while IgG2 and IgG3 levels to Fil.Cho was significantly more in CFA negative subjects when compared to those with CFA. Although IgG1 reacted more readily with Fil.Pro, unlike IgG4, their levels were significantly more in CFA negative subjects when compared to those with active filarial infection. Absorption of sera with phosphorylcholine (PC) resulted in no significant loss of reactivity to Fil.Cho indicating that most of the anticarbohydrate antibodies were recognizing non-PC determinants in human filariasis. Elevated levels of IgG2 and IgG3 antibodies to Fil.Cho in individuals free of filarial infection indicate a possible role for carbohydrate antigens in induction of protective immunity in human filariasis.

Human Bancroftian filariasis: loss of patent microfilaraemia is not associated with production of antibodies to microfilarial sheath

Antisheath antibodies have been incriminated in elimination of circulating microfilariae in human filariasis since a very significant inverse association has been consistently demonstrated between the two parameters. An attempt was made in the present study to seek empirical proof for the above proposal. Two cohorts of 43 and 73 microfilariae (mf) carriers were examined after 13 and 10 years, respectively, for mf as well as antisheath antibodies. The first cohort was also examined for the presence of circulating filarial antigen (CFA). Of the 43 mf carriers examined after 13 years, 62.8% were free of circulating mf although only 3.7% of them had demonstrable antisheath antibodies. Approximately 93% of this cohort (with or without current microfilaraemia) tested positive for CFA after 13 years indicating continued presence of adult filarial worms in the host after loss of mf in circulation. When the second cohort of 73 mf carriers were examined after 10 years, 30 were found to be amicrofilaraemic and only 6.66% of them had demonstrable antisheath antibodies. We conclude that, in human Bancroftian filariasis, elimination of circulating microfilariae may not be mediated by antibodies to microfilarial sheath.

Are inflammation and immunological hyperactivity needed for filarial parasite development?

Immune-dependent growth and development of infectious agents and pathogenesis of disease are increasingly being recognized. It is proposed that the development of filarial larvae to adult stage parasites takes place in an ambiance of inflammatory T helper cell type 1 cytokines in mammalian hosts, and that susceptibility to filarial infections could be governed by the status of macrophage-derived nitric oxide and host ability to produce antibodies to filarial T-independent (carbohydrate) antigens.

Protective immunity in human Bancroftian filariasis: inverse relationship between antibodies to microfilarial sheath and circulating filarial antigens

The existence and the nature of protective immunity in human filariasis continues to be a subject of intense debate. While there is no broad consensus on functional immunity against larval and adult stage parasites, anti-microfilarial immunity has been demonstrated to be mediated by antibodies to the microfilarial sheath. In the present study, circulating filarial antigens (CFA), a marker of active filarial infection in human Bancroftian filariasis, was found to be inversely associated with antibodies to microfilarial sheath in a cohort of 411 subjects representing all categories of filariasis across the clinical spectrum of the disease. Approximately 80% of humans of all age groups (5-65 years) were found to have either CFA or anti-sheath antibodies. The inverse relationship observed between these two parameters was found to be independent of the clinical manifestation; both symptomatic and asymptomatic cases were found to display similar inverse association between CFA and anti-sheath antibodies. The prevalence of anti-sheath antibodies in the paediatric group was found to be very high as compared to adults; 78% of children below the age of 10 years tested positive for anti-sheath antibodies although the mf rate and CFA rate were only 4.5% and 22.7%, respectively, in this age group, indicating that developing larvae or juvenile adult stage parasites could have been the source of antigenic stimulus for induction of antibodies to the microfilarial sheath.

Setaria digitata infections in cattle: parasite load, microfilaraemia status and relationship to immune response

A total of 110 cattle were examined in an area endemic for Bancroftian filariasis for the prevalence of infection of the bovine filarial parasite Setaria digitata. About 12.5% of cattle were found to harbour both adult worms in the peritoneum and microfilariae (mf) in circulation; 70% of the cattle were amicrofilaraemic but with an adult worm infection. A third group of cattle (16.5%) was free of detectable mf and adult worms. The presence of adult worms and/or mf did not influence the antibody levels to any of the four antigen preparations of S. digitata. However, there was a significant inverse relationship between the presence of antibodies to microfilarial sheaths and the absence of circulating mf as shown by the immunoperoxidase assay. Cattle immunoglobulin containing high titres of anti-sheath antibodies cleared circulating microfilariae very effectively in Mastomys coucha thus demonstrating the protective nature of anti-sheath antibodies in eliminating circulating microfilariae in vivo.

Detection of antigen-specific human serum proteins related to the T-cell receptor in infectious disease and in an immune response to milk proteins or chemicals

A monoclonal IgG2 antibody, MG3C9-1 A12, was prepared by immunization of mice with human serum Cohn Fraction III proteins enriched for TCR Ca+ proteins. MG3C9-1 A12 bound to Mr 28,000, antigen-specific TCR Ca+, beta-, and TCR Ca+, beta+ serum proteins associated with TGF-beta1, 2. The IgG2 monoclonal antibody also bound to T-lymphocyte proteins but did not bind to B lymphocyte proteins, human albumin, IgM, IgG, IgA, or TGF-beta1, 2, 3 immunogenic peptides. Monoclonal MG3C9-1 A12 detected TCR-related proteins specific for filarial extract, milk proteins, or benzoic acid in the sera of individuals with chronic or asymptomatic filariasis, milk intolerance, or sensitivity to toluene, respectively. TCR-related serum proteins were also detected intracellularly in mononuclear cells in frozen sections of ileum from a patient with milk intolerance and reactive mesenteric lymph nodes from a patient with a gastric ulcer. The results suggest that antigen-specific TCR-related serum proteins may be elevated during an immune response to oral, environmental, or infectious stimuli.

Urinary diversion after total pelvic exenteration for rectal cancer

BACKGROUND

Total cystectomy is indicated for the treatment of bulky primary rectal cancers as well as previously treated, locally recurrent tumors that invade the bladder, prostate, seminal vesicle, or urethra. We review a 10-year Memorial Sloan-Kettering Cancer Center experience with urinary diversion in this setting.

METHODS

Between April 1988 and June 1998, 47 patients underwent urinary diversion during a total pelvic exenteration for rectal cancer. Charts and operative records were reviewed to determine pathological findings, short-term and long-term urological complications, and survival.

RESULTS

Forty-seven patients (25 males and 22 females; median age, 62 years; age range, 27-79 years) were included. Sixteen (34%) patients underwent cystectomy for a primary rectal tumor (including 1 for rectal sarcoma and 1 for synchronous invasive bladder cancer), and 31 (66%) patients underwent surgery for a locally recurrent rectal cancer. Thirty (64%) patients underwent preoperative, 18 (38%) underwent intraoperative, and 11 (23%) underwent postoperative radiotherapy. Twenty-six (55%) patients received preoperative and 16 (34%) underwent postoperative chemotherapy. Two patients had continent ileal cecal reservoirs, 1 a colonic conduit, and the remaining 45 had ileal conduits. The tumor invaded the bladder in 24 (51%) patients, the prostate in 5 (11%) patients, and the seminal vesicle in 5 (11%) patients. Complete resection was achieved in 42 (89%) patients. There were a total of eight complications in eight (17%) patients. There were three early complications, two of which were ileoureteral anastomotic leaks, one managed by reoperation, the second by percutaneous drainage, and one moderate hydronephrosis managed expectantly. There were five late complications; three patients had ureteral stricture/stenosis, leading to nephrectomy in one patient and percutaneous stenting in two patients. Two patients developed late hydronephrosis, so far managed expectantly. There was one perioperative death. After a median follow-up of 16.83 months, 20 patients were dead of the disease, 6 were alive with disease recurrence, 2 were dead of other causes, and 19 had no evidence of disease. Three-year actuarial disease-specific survival was 34%.

CONCLUSIONS

Complete resection of bulky primary or locally recurrent rectal cancer can be performed with acceptable urological morbidity. Complete resection was obtained in 89% of patients, with 72% having urological organ invasion. Overall urological complications of 17% are acceptably low despite intensive perioperative radiation and chemotherapy. Disease-specific survival in these patients remains limited.

Naturally occurring alpha-galactosyl antibodies in human sera display polyreactivity

Anti-gal is a dominant autoantibody constituting nearly 1% of total circulating IgG in humans and old world primates. Raised levels of anti-gal have been demonstrated in parasitic diseases such as malaria, leishmaniasis and Chagas disease and in a variety of autoimmune diseases. It has also been implicated as a primary cause of rejection of xenogeneic cells and organs transplanted in old world primates since Gal-alpha 1,3 Gal is thought to be the major antigenic epitope to which xenoreactive natural antibodies bind. Since polyreactive antibodies have also been widely implicated in xenotransplantation and anti-gal is yet to be demonstrated to be polyreactive, we have attempted to study this property of anti-gal antibodies. Anti-gal levels were assayed in 72 human sera and compared with DNA-binding antibodies. A significant positive correlation was found between anti-gal and DNA-binding antibodies. Absorption of sera with fresh rabbit erythrocytes (which express abundant alpha-galactose on their surface) resulted in significant removal of both anti-gal and DNA-binding antibodies. Affinity purified anti-gal were found to be reactive to DNA, actin, myosin and tubulin indicating the polyreactive nature of naturally occurring anti-gal antibodies in human sera. The observed polyreactivity was not an exclusive feature of sera collected from tropical countries-anti-gal affinity purified from sera of North Americans were also found to react with DNA. The demonstration of polyreactivity of anti-gal indicates a much wider biological role for this autoantibody in humans and old world primates.

Bruton's tyrosine kinase deficiency in macrophages inhibits nitric oxide generation leading to enhancement of IL-12 induction

We show that macrophages of X-linked immunodeficient mice with a mutant nonfunctional Bruton's tyrosine kinase produce less NO than wild-type macrophages in response to a variety of stimuli. Induction of the inducible NO synthase (iNOS) protein, the transcription factor IFN regulatory factor-1 involved in iNOS expression, and the transcription factor STAT-1 involved in regulating IFN regulatory factor-1 induction are all poorer in X-linked immunodeficient than in wild-type macrophages. On the other hand, induction of IL-12 is higher in X-linked immunodeficient than in wild-type macrophages. Macrophage IL-12 induction is enhanced by iNOS inhibitors such as aminoguanidine and thiocitrulline and is inhibited by NO generation via sodium nitroprusside. There is relative enhancement of IFN-gamma production by immune T cells from mice immunized under aminoguanidine cover. Our data thus suggest that Bruton's tyrosine kinase participates in signaling for iNOS induction via IFN regulatory factor-1 in macrophages and that NO is an inhibitor of IL-12 induction.

Delayed clearance of filarial infection and enhanced Th1 immunity due to modulation of macrophage APC functions in xid mice

Bruton's tyrosine kinase (Btk) mutant CBA/N mice show delayed clearance of injected microfilaria (mf) compared with wild-type CBA/J mice. Anti-mf T cells from CBA/N mice make relatively more IFN-gamma than those from CBA/J mice. The anti-mf T cell proliferative responses are also greater in CBA/N mice. This CBA/N immune phenotype is not restricted to filarial Ags, because immunization with pure proteins also yields T cell responses of greater proliferative magnitude skewed away from Th2 cytokines in CBA/N compared with CBA/J mice. The increased magnitude of CBA/N T cell proliferative responses is reflected in increases in both precursor frequencies and clonal burst sizes of responding Ag-specific T cells, and is independent of the source of re-stimulating APCs. Transfer of CBA/J peritoneal resident cells (PRCs) into CBA/N mice before pure protein immunization leads to a wild-type immune phenotype in the recipient CBA/N mice, with a reduction in the proliferative response and a relative decrease in the IFN-gamma produced. When wild-type PRC subpopulations are similarly transferred, the wild-type immune phenotype is transferred by macrophages rather than by B cells. Transfer of wild-type PRCs into CBA/N mice before injection of mf also causes similar changes in the anti-mf T cell responses and enhances the clearance of mf. Thus, Btk is involved in critical macrophage APC functions regulating priming of T cells, and can modulate these responses in pathophysiologically relevant fashion in vivo.

Lymphatic filariasis and malaria: concomitant parasitism in Orissa, India

Concomitant parasitism with Plasmodium spp. and Wuchereria bancrofti was examined in Orissa, India, to study the influence of one parasite infection on the other in human communities. A survey of 1815 nocturnal blood films in 11 villages indicated an overall prevalence of 9.6% for malaria and 8.5% for microfilaraemia. Only 0.3% of the population harboured both parasites. Analysis of the expected and observed distribution of cases of dual infection in each village did not indicate any significant interaction between the 2 infections. The malarial vector density in 3 selected villages correlated well with the prevalence rate of malaria.

Antibodies to diethylcarbamazine potentiate the antifilarial activity of the drug

The antifilarial drug diethylcarbamazine citrate (DEC) is known to mediate in vivo microfilaricidal activity in conjunction with the host immune system. In this study passive transfer of antibodies to DEC elicited by immunization with methyl piperazine carboxylic acid (MPCA) coupled to bovine serum albumin (BSA), was found to potentiate microfilaricidal activity of subcurative doses of DEC in Setaria digitata infected Mastomys coucha. Active immunization of microfilaraemic animals with MPCA-BSA followed by administration of subcurative doses of DEC also resulted in rapid clearance of microfilaraemia in both S. digitata and Brugia malayi infected M. coucha indicating the synergistic activity of DEC and the antibodies to the drug. Since some of the filarial antibodies are known to react with DEC, it is proposed that such antibodies may potentiate the microfilaricidal activity of the drug in vivo.

Engagement in Academic Work: The Role of Learning Goals, Future Consequences, Pleasing Others, and Perceived Ability

Engagement in academic work was viewed from a multiple goals perspective. Two studies were conducted in which high school math students completed an instrument measuring five goals students might have for doing academic work (learning goals, performance goals, obtaining future consequences, pleasing the teacher, and pleasing the family), perceived math ability, self-regulatory activities, strategies (deep or shallow) used when studying for math, and the amount of effort and persistence expended on the class. Factor analysis indicated that the five goals scales and the perceived ability scale represented unique factors. The correlations among the variables revealed theoretically consistent interrelationships. Multiple regression analyses indicated that various goals (e.g., learning goals, obtaining future consequences, and pleasing the teacher), perceived ability, and some interactions accounted for significant amounts of variance in the task engagement measures (self-regulation, strategy use, effort, and persistence) and achievement. Results are discussed in relation to current theory and their practical implications.

Setaria digitata microfilaraemia in Mastomys coucha: an animal model for chemotherapeutic and immunobiological studies

Intraperitoneal implantation of adult gravid females of the bovine filarial parasite, Setaria digitata in Mastomys coucha was found to induce microfilaraemia lasting for about 125 days. The microfilariae (mf) could be detected as early as 4 days post-implantation (p.i.) and peak levels of about 30 mf in 20 microliters of blood were observed by 21 days. A significant positive correlation was found between mf density and the body weight of recipients pre-implantation. The implanted adult worms were generally viable only for less than 1 week. Implantation resulted in a significant decrease in total leucocytes and erythrocytes, induction of eosinophilia, splenomegaly and anti-erythrocyte autoantibodies. The microfilariae in circulation developed into 3rd-stage infective larvae (L3) when fed onto Aedes aegypti (refm, Liverpool strain). The mf in circulation were found to be eliminated by oral administration of diethylcarbamazine citrate, indicating the usefulness of this model for screening potential anti-microfilarial drugs. During the microfilaraemic phase, priming with tetanus toxoid (TT) resulted in significantly decreased production of anti-toxin levels indicating a state of generalized immunosuppression. Induction of antibodies to various fractionated antigenic components of adult parasites could be demonstrated by enzyme immunoassay (EIA) in M. coucha implanted with live or cold-stunned adult worms. The S. digitata-M. coucha model thus is found amenable to perform chemotherapeutic and immunobiological investigations in experimental filariasis.

A role for tumour necrosis factor-alpha in acute lymphatic filariasis

A spectrum of clinical manifestations is a feature of human lymphatic filariasis. The acute disease is characterized by periodic and self limiting episodes of adenolymphangitis, fever and associated constitutional symptoms, while the chronic disease includes long lasting manifestations such as lymphoedema and/or hydrocoele. The microfilariae carriers are generally free of clinical symptoms. In the present study circulating Tumour Necrosis Factor (TNF-alpha) was measured in human bancroftian filariasis with different clinical manifestations. Significantly elevated levels were observed only in patients with acute disease and not in microfilariae carriers or in patients with chronic manifestations. A detailed analysis of the acute cases indicated an absence of correlation between TNF-alpha levels and duration of the episodes. However, a significant positive correlation was observed between the severity of the disease and the TNF-alpha levels. About 85% of the acute cases with severe manifestations showed raised levels of TNF-alpha while only 6.5% of mild cases showed such levels. Manifestation of fever was also significantly associated with higher levels of TNF-alpha-while 80% of acute cases with fever had significant levels only 24% of acute cases without fever had high levels of TNF-alpha. Based on these observations we propose a mediatory role for TNF-alpha in acute filariasis and the possible use of TNF-alpha inhibitors for clinical management of the disease.

A quantitative cell-ELISA for alpha-galactose specific antibodies in human malaria

Naturally occurring antibodies to alpha-linked galactose (anti- gal) has been reported to be present in large quantities in normal human sera and they seem to play an important role in a variety of infectious as well as autoimmune diseases. A cell-ELISA using glutaraldehyde fixed normal rabbit erythrocytes was developed for quantification of anti-gal in human sera. This assay was compared with three other(commonly used) immunoassays viz. a) agglutination b) enhanced agglutination and c) lipid ELISA-assays for detection of anti-gal in human sera. The cell-ELISA was found to be the most sensitive assay followed by lipid-ELISA, enhanced agglutination and agglutination assay in decreasing order. Anti-gal affinity purified through a column of melibiose-agarose was tested by cell-ELISA. Monolayers of RRBC pre-treated with alpha-galactosidase was not reactive while in monolayers treated with beta-galactosidase, the anti-gal reactivity was comparable to those in untreated RRBC monolayer, thus indicating the high specificity of cell-ELISA for detection of antibodies to alpha-linked galactose.

A prognostic role for anti-phosphatidyl choline antibodies in human cerebral malaria

Anti-phosphatidyl choline antibodies (alphaPC) have been measured in adult patients from Orissa, India with Plasmodium falciparum infection of varying clinical severity. Significantly raised levels of alphaPC were observed in infected individuals in comparison with controls. The IgG alphaPC were found to be generally more than IgM alphaPC in most cases. The IgG alphaPC levels were significantly more in those cases of cerebral malaria who recovered fully after quinine administration in comparison with fatal cases not responding to quinine therapy, indicating a role for alphaPC in prognosis of adult cerebral malaria. There was no significant difference in levels of alphaPC IgG between non-cerebral and fatal cerebral malaria patients, indicating an absence of a direct protective role in the development of cerebral manifestations. Subgroup typing of IgG with alphaPC activity indicated IgG3 to be the predominant type, followed by IgG2, IgG1 and IgG4. A significant inverse relationship between serum tumour necrosis factor-alpha (TNF-alpha) levels and IgG1 antibodies with alphaPC activity was found, emphasizing the importance of alphaPC in modifying disease severity. These observations appear to give credence to recent reports in the literature indicating that toxic malarial antigens consist of phospholipids and that antibodies to phospholipids (alphaPL) inhibit such antigens in experimental systems.

Bancroftian filariasis-differential reactivity of anti-sheath antibodies in microfilariae carriers

Anti-sheath antibodies have been detected using an immunofluorescent assay (IFAT) in the sera of microfilariae carriers (AS cases) residing in areas endemic for Bancroftian filariasis. Microfilariae (mf) of Wuchereria bancrofti purified from five different mf carriers were used separately as antigen to identify anti-sheath antibodies. The reactivity of sera from AS cases to mf sheath was found to be variable to the five different mf preparations. While as high as 25% of the sera reacted with mf purified from one individual, none of them reacted with mf purified from two other individuals. Such a differential reactivity to the sheath was found to be a feature of antibodies in AS cases only. Sera of seven amicrofilaraemic patients with elephantiasis reacted uniformly with all five mf preparations. The possible existence of polymorphic antigen(s) on the sheath of W. bancrofti mf has been proposed.

Novel proteins of Plasmodium falciparum identified by differential immunoscreening using immune and patient sera

A differential serological screen of a lambda gt11 cDNA expression library of Plasmodium falciparum was performed in an attempt to identify novel and putative host-protective antigens of the parasite. The screening was done with two categories of sera: (i) acute-phase sera obtained from smear-positive acutely infected P. falciparum patients from various regions in India and (ii) immune sera taken from healthy, permanent adult residents of P. falciparum-endemic rural districts of Orissa in eastern India. These adults had not suffered from any clinical malarial symptoms for at least the previous 3 years at the time of serum collection. Sixty-five clones obtained by screening the lambda gt11 library with two immune serum samples were analyzed extensively with a total of 70 acutely infected patient serum samples. Eight of these clones failed to react with any of the patient sera. Each of these eight clones, when tested individually with 92 serum samples from the immune group, reacted with a minimum of 43% of the samples from this category of sera. Thus, these eight epitopes may encode host-protective elements since they are not recognized by antibodies in the patient sera but react exclusively and extensively with the clinically immune set. Sequence analysis of two of these clones reveals that they are novel Plasmodium genes.

Murine malaria: anti-erythrocytic antibodies recognize N-acetyl neuraminic acid residues

A cell-ELISA was developed using monolayers of glutaraldehyde-fixed normal as well as Plasmodium berghei-infected mouse erythrocytes for quantification and characterization of anti-erythrocytic autoantibodies in murine malaria. Testing normal (NMS) and peak parasitaemic sera (PPS) on erythrocyte monolayers treated with trypsin, sodium meta periodate, neuraminidase or heat, and competitive inhibition of antibodies with soluble sialic acid, revealed that some anti-erythrocytic antibodies (which increase during the parasitaemic phase of infection) recognize N-acetyl neuraminic acid (NANA) residues on host erythrocytes. High levels of antibodies to NANA covalently conjugated to bovine serum albumin (BSA) were detectable in PPS. Such antibodies could be significantly absorbed out by preincubation of PPS with mouse erythrocytes (MRBC). Antibodies in PPS, when affinity-purified on a column of Fetuin-Agarose, were found to be reactive to normal as well as parasitized erythrocyte monolayers. Immunoglobulin isotyping and IgG subgroup typing revealed that most of the anti-erythrocytic autoantibodies in NMS were IgM and IgA, while in PPS there was an appreciable increase in IgG2a and IgG3. Affinity-purified anti-NANA antibodies reacted with DNA when tested in an ELISA. There was a significant positive correlation between anti-erythrocytic antibody and DNA-binding levels in NMS as well as PPS. The DNA-binding antibodies in PPS could be effectively absorbed out by preincubation of sera with fresh MRBC. Affinity determination of anti-erythrocytic antibodies eluted from MRBC revealed binding characteristics in the following order: MRBC > single-stranded DNA > double-stranded DNA.

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.