Induction of immunity to Schistosoma mansoni: interaction of schistosomula with accessory leucocytes in murine skin and draining lymph nodes.
A single exposure to radiation-attenuated cercariae of Schistosoma mansoni induces a high level of protective immunity in C57BL/6 mice, which is mediated by Th1 responses. Events in the skin and/or draining lymph nodes early after exposure are crucial for the induction of protection, and we have investigated the interactions of vaccinating parasites with host leucocytes in these 2 locations. We observed extensive lateral spreading of cercarial secretions along layers of the stratum corneum but not between keratinocytes. There was little direct contact with host leucocytes during the first 1-2 days when the parasites lay at the base of the epidermis, but cells accumulated in the underlying dermis. In contrast to normal parasites, attenuated larvae persisted in the dermis for > 10 days, often surrounded by aggregates of macrophages/dendritic cells. Whilst cells bearing MHC II, CD11b or CD11c markers were present in the lymph nodes, particularly in the periphery and paracortical areas, no obvious redistribution was seen as a result of parasite residence there for 5-15 days. However, ultrastructural observations revealed numerous cells with macrophage/dendritic morphology in the vicinity of parasites, in some instances closely adherent to the tegument. The observations strongly suggest that the tegument is a potent source of the antigens which prime the immune system in the lymph nodes of vaccinated mice for a protective response.
Riengrojpitak
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Department of Biology, University of York, UK.
Anderson
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Wilson
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RA
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000469:parasitology; D004431:Ear, External; D000949:Histocompatibility Antigens Class II / Q000737:chemistry / Q000276:immunology; D006790:Host-Parasite Interactions; D007111:Immunity, Cellular; D007150:Immunohistochemistry; D016167:Integrin alphaXbeta2 / Q000737:chemistry / Q000276:immunology; D007962:Leukocytes / Q000276:immunology / Q000469:parasitology*; D008168:Lung / Q000276:immunology / Q000469:parasitology; D008198:Lymph Nodes / Q000276:immunology / Q000469:parasitology* / Q000648:ultrastructure; D016177:Macrophage-1 Antigen / Q000737:chemistry / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D011817:Rabbits; D051381:Rats; D012550:Schistosoma mansoni / Q000276:immunology* / Q000528:radiation effects; D012555:Schistosomiasis mansoni / Q000276:immunology / Q000517:prevention & control*; D012867:Skin / Q000276:immunology / Q000469:parasitology*
D000949:Histocompatibility Antigens Class II; D016167:Integrin alphaXbeta2; D016177:Macrophage-1 Antigen