Charles E. Tanner

The role of complement in hydatid disease: in vitro studies.

Abstract Kassis A. I. and Tanner C. E. 1976. The role of complement in hydatid disease: in vitro studies. International Journal for Parasitology 6: 25–35. Fresh sera from normal humans, guinea pigs, sheep, cotton rats, B10.D2/n Sn mice or infected cotton rats lyse viable protoscoleces of Echinococcus granulosus and E. multilocularis in vitro . This protoscolecidal activity can be abolished by heating at 56°C, EDTA or incubating with cobra venom factor, suggesting that complement proteins participate in this lytic process. Crude unfiltered hydatid fluid, as well as complement-lysed dead protoscoleces, are anticomplementary in vitro and, as such, probably protect viable protoscoleces in vivo against the action of complement. This anticomplementary activity was found to be associated with the calcareous corpuscles. A hypothesis is presented which relates these in vitro findings to the development of the parasite in vivo . It is suggested that the use of formalin during surgery to kill the parasite should be replaced by fresh serum.

Trichinella spiralis: inhibition of sheep hemagglutinins in mice.

Abstract One hundred and twenty-four mice were injected intraperitoneally with sheep red blood cells. The mice had been previously either orally inoculated with T. spiralis (16 mice), or injected intraperitoneally during 7 consecutive days with normal saline (12 mice), normal mouse serum (6 mice), or infected mouse serum (6 mice), normal rabbit serum (6 mice), sera from lightly (36 mice) or heavily infected rabbits (36 mice), and rabbit anti-lymphocyte serum (6 mice). The homologous serum clearly demonstrated an immunosuppressive effect on the production of sheep hemagglutinins; however, it was impossible to conclude that heterologous serum has such an activity since the normal rabbit serum used as control demonstrated the same activity. The inhibition of hemagglutinin production has also been observed in mice infected with T. spiralis . The presence of a suppressive agent released by the parasite or antigenic competition is discussed as the possible mediator of immunological unresponsiveness.

The effect of immunosuppression on secondary Echinococcus multilocularis infections in mice.

Abstract Baron R. W. and Tanner C. E. 1976. The effect of immunosuppression on secondary Echinococcus multilocularis infections in mice. International Journal for Parasitology6: 37–42. The growth of cysts of Echinococcus multilocularis in T-cell depleted A/J mice was studied. Adult thymectomy enhances the metastasis of hydatid cysts but does not significantly affect the total cyst weight. Combined thymectomy and antithymocyte serum (ATS) treatment also increases the metastatic dissemination of the parasite and also significantly increases cyst loads. It is suggested that cell-mediated immunity controls the early phase of Echinococcus infection.

Echinococcus multilocularis in the mouse: the in vitro protoscolicidal activity of peritoneal macrophages.

Abstract Baron R. W. and Tanner C. E. 1977. Echinococcus multilocularis in the mouse: the in vitro protoscolicidal activity of peritoneal macrophages. International Journal for Parasitology 7: 489–495. The larvae of Echinococcus multilocularis are susceptible to the protoscolicidal activity of infected A/J mouse peritoneal cells. It is shown that the effector cell in this response is an activated macrophage. Preincubation of protoscolices in ‘immune’ serum increases their susceptibility to the protoscolicidal activity of infected mouse peritoneal cells. Macrophages activated nonspecifically by BCG or Taenia crassiceps infections also exhibit protoscolicidal activity in vitro . The identity of the effector cell was confirmed by scanning electron microscopy. It is shown that ‘immune’ macrophages adhere to and form close cellular contacts with the protoscolex surface. It is concluded that resistance to hydatid infections is mediated by activated macrophages.

Seroepidemiologic survey of Toxocara canis infection in urban and rural children

A survey to determine the prevalence of Toxocara canis antibody was conducted among children, ranging in age from less than a year to 15 years, attending a diagnostic test centre for routine evaluation. The association of seropositivity with demographic factors was analysed for 449 urban and 524 rural children. The overall prevalence (antibody titre > 1:32 using ELISA) was 17.0. Children living in rural areas had a significantly greater prevalence of antibody (19.5) than urban children (14.0). Increased risk of infection among rural children was associated with age greater than six years ( P = 0.005) and dogs in the household ( P = 0.01), but these factors were not related to the presence of antibody among urban children.

Lesions induced by complement in vitro on the protoscoleces of Echinococcus multilocularis: A study by electron microscopy

Abstract Changes in the ultrastructure of the tegument of Echinococcus multilocularis protoscoleces during complement-mediated lysis in vitro was studied using transmission and scanning electron microscopy. It was found that the total disintegration of protoscoleces by complement proceeds through formation of ‘tegumental bubbles’ and disruption of the external plasma membrane. This sequence of events was evident in the appearance of numerous loose membrane fragments and vesicles, the lifting of the external unit membrane of the microtriches and the release of organelles from the distal cytoplasm. Subsequent events, such as the appearance of a ‘fuzzy’ coat and disruption of the basement membrane, were probably due to autolysis.

Echinococcus multilocularis in the cotton rat: the in vitro protoscolicidal activity of peritoneal cells.

Abstract Protoscolices of Echinococcus multilocularis were incubated in vitro with peritoneal cells and with sera from normal and infected cotton rats. The cells from rats bearing massive subcutaneous and intraperitoneal hydatid cysts rapidly killed protoscolices; normal cells and cells from lightly infected animals did not. Only sera from rats bearing large, subcutaneous cysts displayed significant protoscolicidal activity. These data suggest that the phenomenon whereby large, established cysts of E. multilocularis effectively suppress the establishment, growth, and metastasis of distant foci of infection has an immunological component.

Echinococcus multilocularis: Complement's role in vivo in hydatid disease

Abstract A strong correlation was observed between complement depletion and the rapid development in vivo of large cyst masses of Echinococcus multilocularis . Complement is required for the control of secondary hydatid infections since significantly enhanced infections were obtained after treatment with cobra venom factor. The determination of altered complement levels in hydatid infections might be useful in predicting the growth phase of hydatid infections.

Trichinella spiralis: peripheral blood, intestinal, and bone-marrow eosinophilia in rats and its relationship to the inoculating dose of larvae, antibody response and parasitism.

Abstract Peripheral eosinophilia, preceded by a period of eosinopenia, characterized trichinella infections in 140 rats inoculated with 11 different doses of larvae. Eosinophilia was also evident in the small intestine and in the bone marrow; eosinopenia also occurred in the intestine, but not in the bone marrow. The peak peripheral eosinophil response occurred between days 11 and 27 of infection, depending on the inoculating dose and was independent of the general inflammatory leucocytic reaction. Eosinopenia was more prominent and of longer duration in the more heavily inoculated animals; it lasted for about 4 days in animals inoculated with three larvae per gram body weight and for about 12 days in animals inoculated with 50 larvae per gram body weight. The numbers of circulating eosinophils at the peak response were positively correlated with the inoculating dose and with the number of muscle larvae. The antibody response was independent of eosinophilia in the blood, small intestine, and the bone marrow.

Importance of lymphokines in the control of multiplication and dispersion of Leishmania donovani within liver macrophages of resistant and susceptible mice.

Leishmania donovani is an obligate intracellular parasite of mammalian macrophages. The immunosuppressant cyclosporin A (CsA), which inhibits the production of interleukin (IL)-1, IL-2, and interferon-gamma, increased infections 3-fold without affecting expression of the Lsh gene. The objective of this study was to determine how activation of macrophages by lymphokines affects the multiplication and propagation of the parasite within liver macrophages. Susceptible C57BL/6J and resistant C57L/J mice were treated with 200 mg/kg CsA and then infected intravenously with 10(7) amastigotes. Two weeks later macrophages were collected from the liver by perfusion, plated on coverslips, and incubated for 4, 24, and 48 hr. The percentage of infected macrophages and the number of amastigotes/100 cells were determined after staining the cells with Giemsas stain. The number of infected macrophages and amastigotes per macrophage was significantly greater in animals of both strains that had been treated with CsA. This study demonstrated clearly that lymphokines or other soluble mediators produced by T cells act, in part, to control infection by L. donovani by minimizing both multiplication within macrophages and their dispersion.