sICAM-1 in meningoencephalitis due to Angiostrongylus cantonensis / sICAM-1 en meningoencefalitis por Angiostrongylus cantonensis

INTRODUCTION: Angiostrongylus cantonensis meningoencephalitis is an emergent disease in the Americas. METHOD: Twelve children suffering from eosinophilic meningoencephalitis due to this parasite aged between 6-10 years were studied. Cerebrospinal fluid (CSF) and serum samples were taken simultaneously in the first diagnostic puncture at admission. RESULTS: All cases showed typical findings on the routine CSF and serum analysis: increased CSF total protein, increased Q (CSF/serum) albumin accompanied by eosinophilia in CSF. No intrathecal synthesis of immunoglobulins was found. Mean serum and CSF sICAM-1 values were 337.4 and 3.97 ng/mL. Qalbumin and QsICAM-1 mean values were 4.1 and 6.2 respectively. In 50 percent of the patients an increased brain-derived fraction of sICAM-1 was found. CONCLUSION: It may be suggested that a dynamic of the sICAM-1 brain derived fraction is perhaps associated to the immune response in the evolution of the disease.sICAM-1 may be an agent in negative feedback for eosinophils passage through the blood-CSF barrier into the inflammatory brain response.

INTRODUCCION: La meningoencefalitis por Angiostrongylus cantonensis es una enfermedad emergente en las Américas. MÉTODO: Doce niños con meningoencefalitis eosinofílica por Angiostrongylus cantonensis con edades entre 6 y 10 años fueron estudiados. Se tomaron muestras simultáneas de suero y líquido cefalorraquídeo (LCR) en la primera punción lumbar diagnóstica. RESULTADOS: Todos los casos evidenciaron hallazgos típicos en los análisis de rutina del LCR y suero: incremento de proteínas totales, aumento de la razón albúmina Q (LCR/suero) acompañado de eosinofilia en LCR. No se encontró síntesis intratecal de inmunoglobulinas. Los valores medios de sICAM-1 en suero y LCR fueron de 337,4 y 3,97 ng/mL respectivamente. Los valores medios de Q albúmina y Q sICAM-1 fueron de 4,1 y 6,2 respectivamente. En el 50 por ciento de los pacientes se encontró un incremento de la fracción de sICAM-1 derivado del cerebro. CONCLUSION: Se puede sugerir que la dinámica de la fracción sICAM-1 derivada del cerebro ocurre quizas asociada a la respuesta inmune frente a la enfermedad. sICAM-1 puede ser un agente de retroalimentación negativa para el paso de eosinófilos de la sangre a través de la barrera sangre-LCR en el cerebro inflamado.

Blinded multi-laboratory evaluation of an in-house dot-blot ELISA kit for diagnosis of human parastrongyliasis.

An in-house membrane dot-blot enzyme-linked immunosorbent assay kit, for the detection of specific antibody to a 31 kDa protein of Parastrongylus cantonensis was evaluated in a blinded multi-laboratory study. The kit was provided to technologists, who were trained in its use, from nine regional laboratories of Thailand. With an identical set of 20 coded serum samples and reference positive and negative controls, the kit was found to have a diagnostic sensitivity of 100% and a diagnostic specificity of 100% in all the laboratories. There was no obvious variation in quality among five lots of the antigen-coated nitrocellulose strips evaluated. The shelf life of the kit was > or = 6 months when the test components were stored at 4 degrees C and 18 months at -20 degrees C. The enzyme-linked immunoassay dot technique is easy to perform and does not require sophisticated electrical equipment; the result is available within 3 hours. If appropriate technical training is included, the application of this dot-blot ELISA kit in clinical laboratories throughout Thailand should be possible.

Specific IgG antibody subclasses to Angiostrongylus cantonensis in patients with angiostrongyliasis.

Total IgG, IgG1, IgG2, IgG3, IgG4, IgA and IgM specific antibodies against Angiostrongylus cantonensis somatic antigen were determined by enzyme-linked immunosorbent assay (ELISA) in sera from proven human angiostrongyliasis (PA) cases, clinically suspected angiostrongyliasis cases with eosinophilic meningitis (EM) and healthy control (HC). The specific IgA antibody in each of the patient groups was significantly higher than those of the HC group (p < 0.05). The mean ELISA value of the specific IgM in the PA group was not significantly different from that of the HC group (p > 0.05). However, the mean specific IgM ELISA value in the EM group was significantly higher than that of the HC group (p < 0.05). The levels of the specific IgG and IgG subclasses in both patient groups were significantly higher than in the healthy control (HC) group (p < 0.001). Major differences were evident in the distribution of the IgG subclass antibodies between the patient groups. The IgG1 antibody demonstrated the highest sensitivity and specificity while the IgM and IgA responses were generally poor in both patient groups. The levels of the specific IgG antibody subclasses possibly explain immune responses to the parasite.

Purification of a specific immunodiagnostic Parastrongylus cantonensis antigen by electroelution from SDS-polyacrylamide gels.

A 31-kDa glycoprotein antigen was purified by electrophoresing the crude extract of Parastrongylus cantonensis adult worms in a 12% SDS-polyacrylamide gel, identifying the 31-kDa component with prestained molecular weight standards, cutting the desired gel strip, and then isolating it by electroelution. Antigen fraction of 31 kDa was re-electrophoresed, transferred to a nitrocellulose membrane and found to be reactive with only the sera from patients with parastrongyliasis. No reactive band was observed with the sera from other related parasitic infections, eg, gnathostomiasis, toxocariasis, filariasis, paragonimiasis, cysticercosis and malaria, and the normal healthy control sera. This antigen fraction isolated showed 100% sensitivity and 100% specificity in the enzyme-linked immunosorbent assay (ELISA) for the detection of 31-kDa specific antibody in the sera from patients with parastrongyliasis. The P. cantonensis antigen of 31 kDa has been obtained by this means with a high degree of purity and applied successfully in conventional ELISA for the specific immunodiagnosis of human parastrongyliasis.

Detection of circulating antigens of Parastrongylus cantonensis in human sera by dot-blot ELISA and sandwich ELISA using monoclonal antibody.

A dot-blot ELISA was compared with a previously performed sandwich ELISA for the detection of Parastrongylus cantonensis antigens in sera from patients. Using the same monoclonal antibody and the same sera, 6 of 10 sera (60%) from parastronglyiasis patients were positive in dot-blot ELISA, whereas with sandwich ELISA, 5 of the same patient sera (50%) were positive. The specificity in both assays was 100% using 50 sera from patients with other parasitic diseases; of these, 10 each were from patients with cysticercosis, filariasis, gnathostomiasis, malaria and toxocariasis. The control group consisted of 53 sera from normal health Thais and Malaysians. The sensitivity of the assays was, however, slightly better with dot-blot ELISA and because it is simple, quick and cost-effective, it may be a test of choice for specific diagnosis of human parastrongyliasis.