摘要:

Tumour necrosis factorα has been implicated in protective immune responses to a number of parasitic helminths. However, the final effector mechanisms resulting in death or expulsion of the parasite are unclear. Here we suggest that, by employing phylogenetically conserved mechanisms, the mammalian immune system is able to interfere with helminth development directly and that the protective effects of TNFα in helminth infections may operate via the induction of parasite apoptosi

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-66.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Granulocyte macrophage‐colony stimulation factor (GM‐CSF), which is a haematopoietic cytokine generated by activated T lymphocytes and macrophages during infection, was investigated for its effects on human neutrophil‐mediated killing of asexual blood forms ofPlasmodium falciparum. Pretreatment of neutrophils with human recombinant‐GM‐CSF markedly increased the parasite killing (measured by a radiometric assay), in the presence of normal serum (containing complement), immune serum (IS), purified IgG (from IS) or heat inactivated IS. GM‐CSF pretreatment also enhanced phagocytosis of the parasite by neutrophils and the expression of CR3, FcγRII and FcγRIII receptors. Treatment of neutrophils with a combination of GM‐CSF and TNF resulted in a synergistic increase in phagocytosis and killing of the parasite. The findings suggest that GM‐CSF is likely to form part of the cytokine network responsible for regulating the antiparasitic activity of the neut

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-64.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Three monoclonal antibodies, Hc2, Hc22 and Hc6, were produced against a surface extract of L3Haemonchus contortusand screened against both free living and parasitic stages of the parasite. Hc2 and Hc22 were of IgG2c isotype and their target epitopes were insensitive to periodate treatment. Hc6 was of IgM isotype and its reactivity was sensitive to periodate treatment of the antigen, suggesting that Hc6 is specific for a carbohydrate epitope. Western blotting of larval extracts and staining of live worms demonstrated that Hc2 was specific for the surface of second stage larvae and that the epitope was still present on the protective sheath of third stage larvae but absent from the L3 cuticle itself. Hc22 was found to be specific for a 70–90 kDa antigen on the surface of third stage infective larvae and cross reacted with a higher molecular weight species present on the surface of third stageTeladorsagia circumcincta. Hc6 showed strong binding to three high molecular weight proteins on immunoblots of third stage larvae only, but in contrast to Hc2 and Hc22, showed no binding to the surface of live larvae. These studies demonstrate unique expression patterns of stage specific antigens on the surface of free living and parasiticH. contortuslar

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-63.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Gangliosides were found to be present inEntamoeba histolytica. They were extracted from lyophilized trophozoites of the pathogenic strain HM‐1:IMSS and purified by high performance thin‐layer chromatography. Two resorcinol‐positive bands, comigrating with GM2 and GD1a were demonstrated, revealing the existence of ganglioside molecules inEntamoeba histolytica. The GM2 content, determined as lipid‐bound sialic acid, was 1.5 μg/108amoebae, the content of the GD1a comigrating band was 0.32 μg/108amoebae. The identity of the GM2 comigrating band was confirmed by TLC immunostaining, using the monoclonal anti‐GM2 antibody GMB28. Furthermore, six out of ten anti‐amoeba positive sera selectively reacted with the GM2 comigrating band, as revealed by immunostaining on TLC plates. Absorption tests revealed that preincubation of anti‐amoeba positive sera with standard GM2 was followed by a significant decrease in the reaction with amoeba trophozoites by indirect immunofluorescence. These results demonstrate that a GM2 comigrating component ofEntamoeba histolyticamay be one of the antigens responsible for the appearance of circulating antibodies in patients

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-67.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Early developmental stages of the trematode parasiteFasciola hepaticawere collected from the peritoneal cavity and liver of mice during a ten day infection period. Using one dimensional SDS‐PAGE, differences in protein expression profiles were observed in stages collected on the same day post‐infection in different physiological locations and also in juvenile parasites collected from the same location on different days post‐infection. Four rat monoclonal antibodies were raised against the parasite using lymph nodes draining infected tissues. Three monoclonal antibodies, FY3‐1, FY3‐2 and FY4‐7, were generated using cells from the mesenteric lymph node of recently challenged immune rats, while FY1‐6 was derived from hepatic lymph node cells of a chronically infected rat. The epitope recognized by FY3‐2 appeared to be carbohydrate in nature and was present on the surface of newly excysted juveniles. Immunoblots revealed that the antigens recognized by FY3‐1, FY3‐2 and FY4‐7 were only expressed for two days after infection. In contrast, FY1‐6 recognized epitopes expressed across all developmental stages screened. The rapid changes in protein and antigen expression observed during the early stages of infection may assist the parasite to evade t

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-65.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Rabbit antisera were raised against an antigen present inSchistosoma mansoniadult worms and eggs, and were shown to yield a single immunoprecipitin arc in immunoelectrophoresis and immunodiffusion againstS. mansoniegg and worm antigen extracts. The antisera conferred partial but significant protection (22–30%) against aS.  mansonichallenge when transferred to mice five and six days after the mice had been infected percutaneously with 200 cercariae. The egg and the worm forms of the antigen were immunologically cross‐reactive, but the egg antigen possessed peptidolytic activity that could be inhibited with serine protease inhibitors. In indirect immunofluorescence the rabbit antisera reacted with surfaces of cercariae, five‐day old lung‐stage schistosomula, miracidia and praziquantel‐treated adult worms. Gel‐filtration chromatography demonstrated a relative molecular size of approximately 480 kDa for both the egg and worm forms of the antigen, and lectin‐affinity chromatography indicated both were glycosylated. The serine protease activity and large relative molecular size of egg Sm480 were confirmed by a combination of radiolabelling with tritiated di‐isopropyl fluorophosphate, immunoelectrophoresis and polyacrylamid

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-68.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

We compared the antigenicity of p126Plasmodium falciparumpeptides with predicted antigenic regions identified using the methods described by Garnieret al. (1978) and Chou&Fasman (1974). For this purpose nine differentP. falciparumpeptides were synthesized in accordance with the deduced amino acid sequence of the p126 gene, and their reactivity was tested using an enzyme linked immunosorbent assay against sera from individuals with a natural malaria infection. Both predictive methods gave similar antigenic‐index scores, however, a comparison of these predictive results with data obtained by ELISA showed that the probability of a correct prediction was only around 45% for both cases. Thus, in our view computer softwares could not be used in isolation for screening purposes, and other parameters must also be taken into account when using such software to assess antigenicit

ISSN:0141-9838    

DOI:10.1046/j.1365-3024.1996.d01-62.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY