Parenteral injection of dextran sulfate 500 (DS 500; 50 mg/kg of body weight) into mice caused a complete loss of resistance to a sublethal (2 x 103 to 5 x 103) infection with Listeria monocytogenes. Such loss could be prevented by pretreatment of animals with 3 x 109 heat-killed Bordetella pertussis organisms (PO) 5 to 30 days before the administration of DS 500. The increased phagocytic capacity induced by PO was only exhausted when a fourfold dose of DS 500, effecting complete loss of antibacterial resistance (50 mg/kg of body weight), was administered. Listeriosis in mice treated with DS 500 is characterized by rapid-progressive necro-purulent inflammation of liver and spleen, lack of mononuclear phagocyte response, and 100% lethality within 72 h after infection. In contrast, the time course, extent, and morphological characteristics of listeriosis in animals pretreated with PO before the DS 500 application were not significantly different from those of nonpretreated controls. Evidence is presented that the protective effect of PO is due to activation of the mononuclear phagocyte system, which without such treatment is blocked by the DS 500 administration. The data presented indicate that the protective effect of PO is due only in part to the endotoxic moiety of these bacteria. Differences in the course and morphology of listeriosis in animals with dysfunction of the mononuclear phagocyte system and in animals with deficiency of the cellular immune system are discussed.
1. Six months after feeding a vitamin A free diet the liver content of mice was markedly reduced but not yet completely exhausted. These vitamin A deprived mice were either immunized with sheep erythrocytes or infected with Listeria monocytogenes. In comparison to normal control mice no significant difference ws observed. This indicates that neither the immune system nor the mononuclear-phagocytic system was involved. 2. Mice treated with a high dose of vitamin A showed increased antibody production against sheep erythrocytes and also increased resistance against infection with L. monocytogenes. These experimental findings indicate a stimulatory effect on the immune system and the mononuclear phagocytic system. As a conclusion it is deduced that the term "anti-infective vitamin" does not hold absolutely true for vitamin A, although certain anti-infective properties cannot be denied.
It is generally believed that antibody-mediated immunosuppression can be only produced in non-primed individuals, and that this applies both to experimental animals and Rh-negative women at risk. However, in this paper it is reported that the additional injection of 0.2 ml of an antiserum to sheep erythrocytes (SE) together with a secondary antigenic stimulus of 10(8) SE into mice, primarily immunized by a tiny dose of 5 x 10(5) SE 28 days before, was capable of producing effective suppression of the secondary immune response.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.