Species-related innate resistance to Schistosoma mansoni. Role of mononuclear phagocytes in schistosomula killing in vitro.

Abstract

A B S T R A C T Resistance to infection with the multicellular parasite Schistosoma mansoni has been previously demonstrated to vary among several host species. The current investigation was designed to examine the basis for this species-related resistance in vitro. Adherent peritoneal macrophages or peripheral blood mononuclear cells from several species of host animals were incubated with S. mansoni schistosomula for 18-24 h; parasite viability was then assayed by methylene blue exclusion. Peritoneal exudate macrophages from susceptible species, such as mice (C57B1/ 6) and hamsters killed, respectively, 6.6±2 and 8.0±2% of incubated schistosomula. In contrast, cells from resistant species: rats, guinea pigs, and rabbits, killed 21±2.3, 15±4.6, and 17±5.5%, respectively. Furthermore, blood monocytes from rabbits resulted in a mean of 25.9±2.8% dead organisms. Schistosomula killing by mononuclear phagocytes obtained from resistant species (rats or rabbits) was dependent on the cell/ parasite ratio. Significant schistosomula mortality resulted from culture supernatants of rat macrophages or rabbit monocytes. Killing by cells from both species was significantly reduced upon addition of L-arginine, while catalase reduced killing only by rat macrophages. We conclude that mononuclear phagocytes may play a key role in species-related innate resistance to schistosomiasis; their in vitro schistosomulicidal activity parallels the known in vivo susceptibility of the donor species. Killing is mediated by lysosomal en-

Differential contribution of chemotaxins and opsonins to neutrophil-mediated killing of Schistosoma mansoni larvae

“…Nevertheless, the inhibition of peroxide accumulation does not necessarily eliminate antibody-dependent cell-mediated killing. Release of the nonoxidative enzyme arginase has been associated with parasite killing by macrophages (26) and monocytes (27), and our data suggest that although arginase is not directly toxic, this effector substance is involved in PMN-mediated parasite killing as well. In culture, developing schistosomula utilize large amounts of arginine for protein synthesis (34).…”

Transcriptional Changes in Schistosoma mansoni during Early Schistosomula Development and in the Presence of Erythrocytes

“…The tegument of S. mansoni schistosomula is the major target of the immune response of a population of putatively resistant (PR) individuals in S. mansoni endemic areas of Brazil [66] , and in schistosomiasis resistant rats [67] . By identifying genes that are highly upregulated during this developmental process, particularly those that are accessible to antibodies such as the exposed tegument and gut proteins, a new suite of vaccine antigens can be produced and screened with sera from resistant hosts.…”

Host Mouse Strain Is Not Selective for a Laboratory Adapted Strain of Schistosoma mansoni

“…Some mammals, such as foxes and rabbits, are absolutely resistant (Von Lichtenberg et al, 1962; Peck et al, 1983), while others demonstrate selection of certain S. mansoni genotypes (LoVerde et al, 1985; Bremond et al, 1993). Although rats of the species Rattus rattus can maintain the life cycle, R. norvegicus cannot (Alarcón de Noya et al, 1997).…”