摘要:

SummaryIt has never been explained why it takes so long for humans to develop immunity to malaria, although factors such as antigenic variation, antigenic polymorphism, and poor immunological responses to critical antigens are thought to be important. Models of malaria, particularly in rodents, have not been helpful. The course of malaria infection differs considerably between humans and rodents. Mice rapidly develop immunity whereas for most humans it takes several years of exposure for this to occur. Mice typically exhibit high parasitaemias whereas humans typically do not. A significant difference in the immune response of humans and mice to malaria parasites might, in part, explain these differences. Most humans have a preexisting population of activated malaria parasite‐specific T cells (cross‐reactive T cells) which we have referred to as ‘natural’ T cells, but such cells have not been observed in mice. These cells, many of which secrete interferon‐γ), might control parasitaemia early in the infection, but a by‐product of their further activation by malaria parasites might be disease symptoms. Development of immunity has been thought of as an active process–acquisition of specific antibody and effector T cell responses. However, it might in part reflect induction of tolerance of this preexisting population of disease‐inducing Tcells as a result of chronic parasitaemia. The initial presence of these Th1‐like cells may also impede the development of a Th2‐like response necessary for the production of protective antibodies. Persistent cross‐reactive stimulation may significant

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1995.tb00966.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryWe report the complete sequence of the cDNA encoding an intermediate filament (IF) protein from Onchocerca volvulus. The OVIF cDNA encodes a protein of 613 amino acid residues, which has a predicted molecular weight of approximately 70 kD. The size of the protein encoded by the O VIF cDNA corresponds well with estimates obtained in Western blotting experiments, but these same experiments suggest that Onchocerca sp. may contain at least two IF proteins. To identify the domain(s) of the O VIF protein responsible for immunogenicity in human filariasis patients, fragments of the OVIF cDNA were subcloned into the appropriate pGEX vector and Western blots of the corresponding fusion proteins probed with human sera. Pooled sera from general onchocerciasis or Bancroftian filariasis patients reacted only with the C‐terminal region of the OVIF protein, whereas sowda onchocerciasis sera reacted 1–2 orders of magnitude more strongly and with a number of other epitopes. Immunolocalization experiments implied that the OVIF protein is associated with both muscle and a number of specific membrane layers. These studies provide the basis for evaluation of the protective potential of the OVIF prot

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1995.tb00967.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe effect of the humoral immune response on the weight and fecundity of the hookworm Necator americanus was examined in an endemically‐infected human population. There was a highly significant negative correlation between total IgE levels and parasite weight and fecundity, after controlling for any effects of host age and hookworm burden. This correlation was present both at initial treatment and after 2 years' reinfection. There was a similar negative correlation between the number of eosinophils and hookworm weight and fecundity at initial treatment. Correlations with levels of specific antibodies to N. americanus excretory‐secretory products were weaker and not significant, although there was a trend towards negative correlations with anti‐ES IgE. This is the first field evidence for an effective human immune response to N. americanus. Although the mechanism of this effect is not clear, we suggest that total IgE levels reflected the level of Th2 cell activ

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1995.tb00968.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe proliferative response of human peripheral blood mononuclear cells (PBMC) from healthy donors to Toxocara canis adult worm antigens (TcA) was examined. PBMC from all donors examined (n= 1) strongly responded to TcA in a dose‐dependent fashion after six days of culture, irrespective of their serological reactivity. In contrast, cord blood mononuclear cells did not react to TcA. The proliferation of PBMC in response to TcA was completely inhibited by anti‐HLA‐DR antibody. Purified CD4+T cells reconstituted with autologous irradiated antigen presenting cells (APC) vigorously proliferated in response to TcA, but this was abrogated by pretreatment of APC with paraformaldehyde. Significant IL‐2, IL‐3, IL‐4, IL‐5 andlFN‐j mRNA expression was detected in PBMC stimulated with TcA, with expression peaking at 72 h after stimulation. IL‐1β, IL‐6, IL‐10 and GM‐CSF mRNA expression was also upregulated, peaking at 24 h after stimulation. Taken together, these results suggest that adult T. canis‐derived antigens have the ability to activate human PBMC as conventional antigens, possibly due to their cross‐reactivity, which may be involved in the host defenc

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1995.tb00969.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummarySerum antibody responses to infection with the intestinal helminth Trichinella spiralis in mice remain at low levels for the first ten to 12 days, slowly increasing to high litres around day 20. It is thought that antibody, therefore, has a limited role in the primary immune response raised against this infection and this is confirmed by the inability of primary infection serum to transfer immunity adoptively. High‐responder NIH and low‐responder B10 mice were vaccinated with T.spiralis antigen in Freund's complete adjuvant prior to challenge. This procedure conferred significant protection on NIH mice but not B10. Sera from these mice were transferred into recipients before and during challenge infection. Significant levels of protection were obtained in both strains with both homologous and heterologous sera, even though vaccination itself had not resulted in protection of the B10 donor mice. These data indicate that the B10 strain is potentially capable of making a protective immune response against the intestinal phase of T.spira

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1995.tb00970.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryNitric oxide (NO) was produced when bovine peripheral blood mononuclear cells (PBMC) or purified, adherent PBMC (macrophages) were incubated in vitro with bovine recombinant interferon gamma (Bo rIFN‐γ). NO was produced by cells from naive, uninfected calves as well as by cells from cattle either infected with or recovered from infection with Theileria annulata or Theileria parva. PBMC of cattle undergoing tropical theileriosis (T. annulata infection) or East Coast fever (T. parva infection) synthesized NO spontaneously in vitro. NO was also induced when PBMC of immune, but not of naive, cattle were cultured with T. annulata macroschizont‐infected cell lines. Macrophages alone were not stimulated to produce NO by such infected cells. In vitro establishment of macroschizont‐infected cell lines was suppressed either by incubating sporozoites with S‐nitroso‐N‐acetyl‐DL‐penicillamine (SNAP), a NO releasing molecule, prior to invasion of PBMC or by pulsing developing cultures of trophozoite‐infected cells with SNAP. Proliferation of established macroschizont‐infected cell lines was not affected by SNAP. Taken together with the well documented roles of NO in neurotransmission, vasodilatation, cell and tissue damage and immunosuppression, the results presented here indicate that NO may not only protect cattle against T. annulata and T. parva but, if produced in excess, play a prominent role in the pathogenesis of tropical theileriosis

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1995.tb00971.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryAnti‐interleukin‐4 (IL‐4) treatment o/“Schistosoma japo‐nicum‐infected mice markedly inhibited in vitro secretion of the Th2 cytokines IL‐4 and IL‐5 from antigen‐stimulated spleen cells, but enhanced the secretion of the Th1 cytokine IFN‐γ. IL‐2 secretion was unaffected. Hepatic fibrosis was markedly diminished in anti‐IL‐4‐treated‐mice at ten weeks of infection while granulomas around S. japonicum eggs in the livers were slightly‐to‐moderately increased in size. The number of eggs per worm pair in the tissues and feces did not differ significantly in treated and untreated mice. These findings suggest that Th2 cytokine responses are important in the genesi

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1995.tb00972.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY