摘要:

SummaryLymphokine‐activated macrophages are cytotoxic for larvae of the helminth parasiteSchistosoma mansoni.That soluble secreted factors may mediate this cytotoxicity was suggested by the observation that culture supernatant fluids from stimulated macrophages also exhibited larvacidal activity. These fluids contain the monokine tumour necrosis factor (TNF). Several observations indicated that TNF is directly toxic to schistosome larvae. Cytotoxic sera taken from BCG‐ orS. mansoni‐immunized mice after endotoxin challenge killed schistosomulain vitro, and upon gel filtration the larvacidal factor(s) in the sera co‐eluted with the tumoricidal activity defined as TNF. Recombinant‐derived TNF exhibited direct toxicity to schistosomula at high concentrations, or at lower concentrations in the presence of IFNγ. The larvacidal activity of macrophage supernatant fluids was abrogated by addition of either anti‐TNF antisera or Zn+2, which has been shown to inhibit TNF‐induced damage of tumour cells. Anti‐TNF and Zn+2likewise suppressed schistosomulum killing by lymphokine‐activated peritoneal macrophages or the IC‐21 macrophage line, indicating that TNF also plays a role in the effector mechanism of larval ki

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1990.tb00932.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummarySerum or immunoglobulin fractions of serum from CBA/Ca mice vaccinated three or four times with radiation‐attenuated cercariae ofSchistosoma mansonihave been investigated for their capacity to confer protection upon naive mice. The data confirm that around 35% protection can be transferred with polyvaccine mouse serum administered in 0.5‐ml aliquots 1 h before challenge (intravenously) and 24 h post‐challenge (intraperitoneally). We show in addition, however, that polyvaccine serum is also protective when injected into the skin site of challenge as a single 0.05‐ml aliquot. In contrast, lymphocytes obtained from the donors of protective serum conferred only 13% protection upon recipient mice. The passive cutaneous anaphylaxis assay showed that IgGl is incremented by polyvaccination, while passive transfer experiments revealed that of the different isotypes fractionated from whole protective serum, only IgG 1 has the capacity to protect naive recipients against challenge. The resistance transferred by IgGl represents more than 60% of that obtained with whole serum and can be achieved using either the intravenous/intraperitoneal or the subcutaneous administration regimen. Recipients of serum given via the subcutaneous route exhibit cutaneous inflammatory focal reactions which comprise 20% eosinophils and 80%i mononuclear cells; these foci entrap challenge larvae. The importance of IgGl subclass expression to the success of serum‐transferred resistance is

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1990.tb00933.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryHeat‐stable antigens of rodent malarial parasites induce the release of tumour necrosis factor (TNF) from mouse macrophages,in vitroandin vivo.We report here that analogous antigens ofPlasmodium falciparumtrigger the release of TNF from human monocytesin vitro, in conditions that exclude the effects of any contaminating endotoxin. These antigens also induced TNF release from a murine monocytic cell line and from the peritoneal macrophages of several strains of mice, including the LPS‐hyporesponsive C3H/HeJ mice. Similarly, boiled soluble antigens from the rodent parasitesP. yoeliiandP. bergheialso stimulated human monocytes. Antisera made by immunizing mice with boiled antigens ofP. falciparumorP. yoeliiinhibited the stimulation of TNF secretion byP. falciparumantigens. They did not block the induction of TNF by bacterial lipopolysacchar‐ide. Thus mouse macrophages provide a convenient system for investigating the nature, cross‐reactions and antigenic variation of human malarial soluble antigens. Since these are known to occur in the circulation of patients with malaria, they may be responsible for excess production of TNF, a mediator that is thought to play a central role in the pathogenesis of the

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1990.tb00934.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryWe describe here a rodent malaria model using cloned lines ofPlasmodium chabaudi chabaudiin inbred CBA/Ca mice that exhibits both clonal antigenic variation in late stage‐specific surface antigens, and deep vascular schizogony in the liver. We show that both these features are modulated by the spleen, and that surface antigen expression is crucially involved in the sequestering phenotype. Surface antigens are variant in chronic infection, and host protective immune responses can distinguish between these variants. Splenectomy abolishes this difference. The acute infection with non‐sequestering cloned lines is kinetically indistinguishable from sequestering clones, but parasites unable to express variant sequestration‐associated antigen do not form a chronic recrudescing infection. Another clone, able to re‐express this antigen in the presence of the spleen, undergoes typical chronic recrudescence. In this model, the biological significance of sequestration‐associated variant antigen seems to enable the establishment of chronic infection in the presence of a prim

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1990.tb00935.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryInfection withTrypanosoma cruziwas established in the reduviid vector,Dipetalogaster maximus, by repeated feedings on mice with high parasitaemias, and metacyclic trypomastigotes (IMT) were collected in insect urine after blood meals. The infectivity of IMT in mice was assessed by placing varying numbers of organisms, ranging from 5 to 5000, on to the conjunctivae or oral mucosa of anaesthetized animals. Half of the mice exposed to as few as 20 IMT by either route became parasitized, and the minimum inoculum size that resulted in all mice becoming infected was 640 IMT by the ocular route and 1250 IMT in the mice given parasites by mouth. Mice were immunized by tail vein infusion of irradiated IMT. Animals in the immunized group and in two control groups were then challenged by deposition of IMT on to the oral mucosa. Two of five immunized mice and nine of 10 comparison animals developed acuteT. cruziinfection after challenge. These results indicate that IMT produced in this system are highly infective and that inocula containing 500–1000 IMT applied to the conjunctivae or oral mucosa constitute a gentle contaminative challenge. Moreover, our findings suggest that sterile protection against a contaminative challenge may be inducible by immunization with IMT, but experiments involving larger numbers of animals must be performed to resolve this questio

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1990.tb00936.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryHereford cattle (Bos taurus) were immunized with antigens solubilized with Triton X‐100 from larval membranes of the cattle tick (Boophilus microplus). Based on tick egg production compared to control cattle, vaccinated cattle were protected (78%) against challenge with 2 × 20000 tick larvae. The soluble Triton X‐100 extract of tick larval membranes was further purified by immunoaffinity chromatography, using immunoglobulin ligands (IgG1 and IgG2) from three immune steers, previously vaccinated with membrane antigens from the midgut of partly engorged adult female ticks. Cattle vaccinated with these purified antigens were protected in two separate experiments (80 and 89% respectively), against challenge with 2 × 20000 larval ticks compared to control cattle. Whole larval membranes used as vaccines in cattle reduced the amount of eggs produced from ticks by 47% compared to control cattle, but this difference was not signif

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1990.tb00937.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

SummaryA sensitive and specific enzyme‐linked immunosorbent assay (ELISA) was developed for mouse intestinal mast cell proteinase (IMCP). Specificity was demonstrated by the absence of immunoreactivity with extracts of isolated serosal mast cells (SMC), or with high concentrations (50 μg/ml) of the antigenically similar rat mast cell proteinases I or II. The small and large intestines in normal mice were the major sources of IMCP, there being little or no IMCP in non‐mucosal tissues. Concentrations of IMCP in normal (non‐parasitized) mice were low, but were increased 100–1000‐fold in intestines of mice infected 10 days earlier withTrichinella spiralis.The kinetic response of secreted IMCP into the blood of mice following infection withT. spiraliswas also studied. Systemic release of IMCP coincided with the immune expulsion of adult worms from the intestine, and peak concentrations (9.45 μg/ml IMCP) occurred 9 days after infection. The tissue distribution of IMCP, its secretion into blood, and its enteric accumulation during parasite infection, are consistent with a mucosal mast cell (MMC) source for IMCP. The results are discussed in the context of similar findings for rat mast cell pr

ISSN:0141-9838    

DOI:10.1111/j.1365-3024.1990.tb00938.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY