Biomedical subjects
Publications and source records attributed to A R Capron.
Significant advances have been made during the past years in our knowledge of schistosomiasis, the second major parasitic disease in the world. The highlights provide a good illustration of the recent progress made in our understanding of immunity in human populations and the regulation of the immune response, and in the approach toward a vaccine.
Mice infected with Schistosoma mansoni at day 0 were given cyclosporin A (Cy-A) from day 1 to day 3 and reinfected at day 45. They were perfused to recover worms at day 66, at which time mature and immature worms, established from infection and reinfection, respectively, could easily be distinguished. A high degree of protection (90-100%) was obtained against both primary and secondary infection. Elimination of the parasites was an early event since only 10-30% of schistosomula, as compared to those in control mice, were recovered at day 6 by pulmonary perfusion. Our data indicate that a direct effect of Cy-A cannot be demonstrated. Nevertheless, Cy-A did evoke a high level of protection against schistosome infection.
Inflammatory macrophages from mice i.p. injected with FCS 24-hr before harvesting, activated by partly purified MAF from Con A-stimulated spleen cells, were shown to kill an average of 60.9% (SE +/- 5.3) of the parasites in cultures of Schistosoma mansoni schistosomula. On the contrary, resident macrophages were not cytotoxic under the same conditions. The degree of macrophage activation for the killing was dependent upon both lymphokine concentration and time of incubation in lymphokine. The capacity of macrophages to be activated to kill schistosomula as well as the schistosomulicidal activity of the lymphokine-activated macrophages were short-lived properties. The killing was strongly influenced by the effector-to-target ratio. The results are consistent with other data on the immune response in experimental infection and particularly the development of the delayed hypersensitivity. Therefore, among the immune mechanisms that participate in immunity to reinfection, cell-mediated immunity that involves inflammatory macrophages should no longer be restricted to microorganisms and protozoans and could be extended to multicellular parasites like schistosomes.
The presence of IgE antibodies to antigen 5 of Echinococcus granulosus was detected by means of radioimmunoelectrophoresis in the sera of two of six patients infected with E. multilocularis. Sera from three of these patients gave a precipitin band in gel diffusion tests identical to that produced by a monospecific rabbit anti-E. granulosus antigen 5 serum, when tested against whole hydatid fluid. Sera from 19 individuals infected with Fasciola hepatica, 20 with Schistosoma mansoni, and 5 with with Taenia saginata showed no detectable antibodies against antigen 5 of E. granulosus, The monospecific rabbit anti-E. granulosus antigen 5 serum did not react in immunodiffusion with homologous antigen when absorbed with either 4 mg/ml of whole hydatid fluid or with 200 mg/ml of a soluble E. multilocularis extract. Absorption of the monospecific antiserum with crude antigens of either F. hepatica, Onchocerca volvulus, S. mansoni, or T. saginata did not abolish the reaction with antigen 5. It appears, therefore, that antigen 5 can no longer be considered specific for E. granulosus, but is also present in E. multilocularis. In the light of this observation, some reevaluation of immunodiagnostic tests in hydatid disease will be necessary.
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