Humoral immune response in patients with cerebral parenchymal cysticercosis treated with praziquantel

Immunological and molecular diagnosis of cysticercosis

Cysticercosis, the infection with the larval stage of Taenia solium, is a cause of neurological symptoms including seizures, affecting the quality of life of patients and their families. Diagnosis focuses on brain imaging and serological tests are mostly used as confirmatory tools. Most cases, however, occur in poor endemic areas, where both kinds of diagnostic tools are poorly available. Development of point of care diagnostic tests is one of the most important priorities for cysticercosis researches today. The ideal point of care test would require detection of viable cysticercosis and hopefully identify cases with severe or progressive forms of neurocysticercosis, leading to referral of the patient for specialized medical attention. This manuscript describes the evolution of the serological diagnosis of cysticercosis over time, and the characteristics of the most common currently available tools, their advantages and disadvantages, and their potential use in future diagnostic tests.

Detection of Taenia solium antigens and anti-T. solium antibodies in paired serum and cerebrospinal fluid samples from patients with intraparenchymal or extraparenchymal neurocysticercosis

BACKGROUND

Neurocysticercosis (NCC) is a frequent cause of epilepsy worldwide. Compared with the more common parenchymal brain cysts, extraparenchymal infections are difficult to manage and have a poor prognosis. Serological assays are used to detect circulating Taenia solium antigens or anti-T. solium antibodies in serum or cerebrospinal fluid (CSF) samples. There are no guidelines on whether to use serum or CSF specimens for a particular assay.

METHODS

We obtained paired serum and CSF samples from 91 patients with NCC (48 had intraparenchymal NCC, and 43 had extraparenchymal NCC) for detection of antibodies, using an enzyme-linked immunotransfer blot (EITB) assay, and antigens, using a monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA).

RESULTS

For the intraparenchymal NCC group, the EITB assay yielded more true-positive results for serum samples, and the ELISA yielded slightly more true-positive results for CSF samples than for serum samples, but none of these differences were statistically significant. Most patients with calcified NCC were antibody positive but antigen negative. For extraparenchymal disease, all samples were antibody positive, and all but 2 were antigen positive, with most samples containing high antigen levels.

CONCLUSIONS

The sensitivity of antibody-detecting EITB assays is not increased through the use of CSF samples rather than serum samples. The antigen-detecting ELISA performed better for CSF samples than for serum samples, but for both specimen types it was less sensitive than the EITB assay. Active and inactive NCC are better differentiated from each other by the antigen-detecting ELISA, for both serum and CSF samples. High antigen levels suggest the presence of subarachnoid NCC.

CSF/serum quotient graphs for the evaluation of intrathecal C4 synthesis

Background

Cerebrospinal fluid (CSF)/serum quotient graphs have been used previously to determine local synthesis in brain of immunoglobulins and C₃ complement component. The aim of this study was to use the same technique to construct quotient graphs, or Reibergrams, for the beta globulin C₄ and to evaluate the method for assessing intrathecal synthesis in neurological disease.

Methods

The constants in the previously-defined Reibergram for immunoglobulin IgA were used to calculate the CSF/serum quotient for C₄. CSF and serum were analyzed for C₄, IgA and albumin from a total of 12 patients with meningoencephalitis caused by encapsulated microorganisms and 10 subjects without infections or inflammatory neurological disease, some of which had dysfunction of the blood-CSF barrier,

Results

The formula and C₄ Reibergram with the constants previously found for IgA, determined the intrathecal C₄ synthesis in CSF. The intrathecal C₄ fraction in CSF (C₄ loc in mg/l) was compared to the C₄-Index (fraction of CSF: serum for C ₄/fraction of CSF: serum for albumin). There was a significant correlation between the two formulae. The CSF/Serum quotient graph was superior for detecting intrathecal synthesis of C₄ under variable conditions of blood-CSF barrier permeability.

Conclusion

The C₄ Reibergram can be used to quantify the intrathecal synthesis of this component of the complement system in different infectious diseases of the central nervous system and is especially useful for patients with blood-brain barrier dysfunction.

Intrathecal synthesis of specific immunoglobulin G antibodies in neurocysticercosis: evaluation of antibody concentrations by enzyme-linked immunosorbent assay using a whole cysticercal extract and cyst vesicular fluid as antigens

The demonstration of intrathecal antibody production has proven useful for showing the involvement of the central nervous system (CNS) in several diseases. In the present study, the intrathecal synthesis of cysticercus-specific immunoglobulin G (IgG) antibodies was investigated in 30 patients with neurocysticercosis based on calculation of the specific IgG antibody index (AI(IgG)). An AI(IgG) > or =1.5 was considered to be indicative of intrathecal antibody production. Antibody concentrations in serum and cerebrospinal fluid samples were evaluated using an enzyme-linked immunosorbent assay with 2 antigen preparations from Taenia solium cysticerci, namely, a whole cysticercal extract (TsoW) and the vesicular fluid of the parasite (TsoVF). Intrathecal, cysticercus-specific IgG antibody synthesis was observed in 21 (70%) and 23 (76.6%) patients using the TsoW and TsoVF antigens, respectively. The detection of the intrathecal synthesis of specific antibodies may be a potentially useful tool in establishing the involvement of CNS in cysticercosis.

Serodiagnosis of human cysticercosis by using antigens from vesicular fluid of Taenia crassiceps cysticerci

Neurocysticercosis (NC), caused by the presence of Taenia solium metacestodes in tissues, is a severe parasitic infection of the central nervous system with universal distribution. To determine the efficiency of enzyme-linked immunosorbent assay (ELISA) and immunoblot with antigens of T. crassiceps vesicular fluid (Tcra) compared to standard techniques (indirect immunofluorescence test [IFT] and complement fixation test [CFT]) using T. solium cysticerci (Tso) for the serodiagnosis of NC, we studied serum samples from 24 patients with NC, 30 supposedly healthy individuals, 76 blood bank donors, 45 individuals with other non-NC parasitoses, and 97 samples from individuals screened for cysticercosis serology (SC). The sensitivity observed was 100% for ELISA-Tso and ELISA-Tcra, 91.7% for the IFT, and 87.5% for the CFT. The specificity was 90% for ELISA-Tso, 96.7% for ELISA-Tcra, 50% for IFT, and 63.3% for CFT. The efficiency was highest for ELISA-Tcra, followed by ELISA-Tso, IFT, and CFT. Of the 23 samples from SC group, which were reactive to ELISA-Tso and/or ELISA-Tcra, only 3 were positive to immunblot-Tcra (specific peptides of 14- and 18-kDa) and to glycoprotein peptides purified from Tcra antigen (gp-Tcra), showing the low predictive value of ELISA for screening. None of the samples from the remaining groups showed specific reactivity in immunoblot-Tcra. These results demonstrate that ELISA-Tcra can be used as a screening method for the serodiagnosis of NC and support the need for specific tests for confirmation of the results. The immunoblot can be used as a confirmatory test both with Tcra and gp-Tcra, with the latter having an advantage in terms of visualization of the results.

Total IgE detection in paired cerebrospinal fluid and serum samples from patients with neurocysticercosis

Neurocysticercosis (NC), the presence of Taenia solium metacestodes in tissues, is the most frequent and severe parasitic infection of the central nervous system. We investigated the presence of total IgE by an automated chemiluminescence assay in 53 paired cerebrospinal fluid (CSF) and serum samples from patients with NC (P) and in 40 CSF samples from individuals with other neurological disorders as the control group (C). Total IgE concentration ranged from 1.2 to 6.6 IU/ml (mean = 1.4 IU/ml, standard deviation-sd = 1.1 IU/ml) in 28.3% of CSF samples from the P group, a value significantly higher than for the C group ( pound1.0 IU/ml). The serum samples from the P group showed concentrations ranging from 1. 0 to 2330.0 IU/ml (mean = 224.1 IU/ml, sd = 452.1 IU/ml), which were higher than the normal value cited by the manufacturer (<100.0 IU/ml) in 32.1% of the samples. A significant difference was observed in CSF samples from the P and C groups (p = 0.005) and in serum samples from the P group compared to the normal value (p = 0. 005), with sera showing more frequent abnormal results.

Neurocysticercosis: detection of IgG, IgA and IgE antibodies in cerebrospinal fluid, serum and saliva samples by ELISA with Taenia solium and Taenia crassiceps antigens

We assayed samples of cerebrospinal fluid (CSF), serum and saliva from patients with neurocysticercoses, control group and individuals with other parasitoses, by ELISA with Taenia crassiceps vesicular fluid antigen (Tcra) and Taenia solium total antigen (Tso) for the detection of antibodies. The sensitivity for IgG-Tcra was 100% for CSF and serum, and 32.0% for saliva; and for IgG-Tso 100% for CSF, 80.0% for serum and 24.% for saliva. Specificity was 100% for CSF and 80.0% for serum with both antigens, and 100% for saliva with Tcra and 87.5% with Tso. The sensitivity and specificity for IgA-Tcra was, respectively, 40.0% and 100% for CSF, 36.0% and 97.1% for serum, and 4.0% and 90.0% for saliva. IgE detection showed 24.0% sensitivity and 97.1% specificity for serum, with no detection in CSF samples. The search for antibodies revealed the presence of IgG > IgA > IgE in CSF, serum and saliva samples, with IgG being present in all phases of the disease, while IgA/IgE were more frequent in the inactive form.

Specific Taenia crassiceps and Taenia solium antigenic peptides for neurocysticercosis immunodiagnosis using serum samples

Neurocysticercosis (NC), i.e., the presence of the larval form of Taenia solium in tissues, is the most frequent and severe infection involving the central nervous system. Paired serum and cerebrospinal fluid (CSF) samples from patients with NC, CSF and serum samples from a control group, and serum samples from patients with other parasitoses were studied by enzyme-linked immunosorbent assay (ELISA) and by immunoblotting with Taenia crassiceps vesicular fluid antigen (Tcra) and Taenia solium total saline antigen (Tso) for the detection of immunoglobulin G antibodies. ELISAs carried out with the Tso and Tcra antigens showed 94.1 and 95.6% sensitivities, respectively, for the detection of antibodies in CSF and 70.6% and 91.2% sensitivities, respectively, for the detection of antibodies in serum, with 100% specificity for the detection of antibodies in CSF and 80% specificity for the detection of antibodies in serum for both antigens. On the basis of the reactivities of the peptides in the samples analyzed, the peptides of </=23, 39, 85 to 77, and 97 kDa were found to be Tso specific by immunoblotting and the peptides of </=62, 74, 109, 121, and 131 kDa were found to be Tcra specific. Tests with Tcra extract had higher sensitivities and more homogeneous results and permitted us to obtain the parasites easily. We suggest the use of Tcra ELISA for the study of serum and confirmation of the results for sera positive by an immunoblotting analysis in which specific peptides (e.g., peptides of 19 to 13 kDa) are detected.

Pharmacokinetic study of praziquantel administered alone and in combination with cimetidine in a single-day therapeutic regimen

A brief therapeutic regimen of praziquantel, reduced to a single day, has been effective for treatment of neurocysticercosis. To study its pharmacokinetic characteristics, levels of praziquantel in plasma were determined for eight healthy volunteers after the administration of three oral doses of 25 mg/kg of body weight given at 2-h intervals, alone and with the simultaneous administration of cimetidine. Each volunteer received both regimens in a randomized crossover design. Blood samples were taken during a period of 12 h, and praziquantel concentration was measured by high-performance liquid chromatography. Levels of praziquantel in plasma remained above 300 ng/ml during a period of 12 h; they increased 100% when cimetidine was jointly administered. Compared with other regimens, the high levels obtained and the longer duration of action seem to be advantageous in prolonging the exposure of the parasites to the drug and support previous clinical experience showing that the treatment of neurocysticercosis with praziquantel can be reduced from 2 weeks to 1 day with the drug still retaining its cysticidal properties. Moreover, simultaneous administration of praziquantel and cimetidine could improve further the efficacy of the single-day therapy for cysticercosis and other parasitic diseases, such as schistosomiasis.

Neurocysticercosis

Cysticercosis is an infection caused by Taenia solium larvae (cysticerci). When the cysticercus is lodged in the central nervous system (CNS), the disease is known as neurocysticercosis (NCC). NCC is the most frequent and most widely disseminated human neuroparasitosis. It is endemic in many parts of the world, particularly Latin America, Africa, and Asia, and still relatively frequent in Portugal, Spain and Eastern European countries It is also endemic in developed countries with high rates of immigration from endemic areas. Man may act as an intermediate host after ingestion of mature, viable T. solium eggs via the fecal-oral route. The development of lesions in the brain and leptomeninges, and the consequent of onset of symptoms associated with NCC are mainly due to the host immune-inflammatory response. As long as the cysticercus remains viable, there is relative host immune tolerance. It is only when the parasite dies that massive antigen exposure occurs, with intensification of the immune response/inflammatory reaction and the appearance or worsening of symptoms. NCC can be asymptomatic or cause widely varied clinical manifestations, such as seizures, increased intracranial pressure, ischemic cerebrovascular disease, dementia, and signs of compression of the spinal roots/cord. The combination of two or more symptoms is common. Such clinical polymorphism is determined by 1) the number of lesions (single or multiple cysticerci); 2) the location of CNS lesions (subarachnoid, intracerebral, intraventricular, intramedullary); 3) the type of cysticercus (Cysticercus cellulosae, Cysticercus racemosus); 4) the stage of development and involution of the parasite (vesicular or viable, necrotic, fibrocalcified nodule); and 5) the intensity of the host immune-inflammatory response (no inflammatory reaction, leptomeningitis, encephalitis, granular ependymitis, arteritis).

Use of enzyme-linked immunosorbent assay and enzyme-linked immunoelectrotransfer blot for the diagnosis and monitoring of neurocysticercosis

A total of 70 proven cases of neurocysticercosis from la Réunion (Indian Ocean) were studied with enzyme-linked immunoassay (ELISA) and immunoelectrotransfer blot (EITB) to detect specific antibodies in serum and cerebrospinal fluid (CSF). Absorbance levels of antibody to crude Taenia solium cyst extract as an antigen were compared with EITB banding-pattern and computed tomography-scan results. The EITB analysis of sera and CSF from patients with active neurocysticercosis, confirmed with characteristic brain-scan imaging and highest ELISA absorbance, regularly revealed two bands with molecular weights of 13 and 14 kDa, respectively. These low-molecular-weight fractions are potential markers of active cerebral cysticercosis, a result obtained in the simple epidemiological situation of La Réunion (Indian Ocean). A parallel study is underway in Madagascar, where cross-reactivities with other parasitic diseases, including Schistosoma infections, may interfere.

High-dose intravenous-penicillin in neurosyphilis: effect on intrathecal synthesis of IgG, IgM, IgA and IgD

We evaluated occurrence and levels of intrathecal synthesis of IgG, IgM, IgA and IgD by calculating corresponding index values in 8 patients with definite and 4 with suspected or possible neurosyphilis, prior to, during and after high-dose intravenous penicillin therapy. Four patients with active neurosyphilis displayed intrathecal synthesis of IgG, IgM and IgA. Only 2 of them showed elevated IgD index, and both had taboparesis, pleocytosis and positive VDRL in CSF, and simultaneous elevation of the IgG, IgA and especially of the IgM indices. This suggests that intrathecal synthesis of IgD may occur in patients with severe CNS inflammation in response to diffuse CNS treponemal damage. Penicillin therapy incited transitory elevation of one or more of the immunoglobulin index values in most patients, possibly in response to massive treponemal lysis inside the CNS. Thereafter, the values became mostly normalized but exceptions occurred, including one patient who had elevated IgG and IgM index which persisted 31 months after therapy. Our data indicate that determinations of immunoglobulin indices performed on consecutive specimens from individual patients with neurosyphilis may be helpful in the evaluation of treatment.