title: Induction of type 2 responses by schistosome worms during prepatent infection.
abstract: During natural schistosome infection, the induction of T helper type 2 (Th2) responses has been ascribed to parasite eggs, because exposure of the host to this life-cycle stage elicits a polarized Th2 response to egg antigens. In the present study, we show that schistosome worms also elicit systemic, antigen-specific type 2 responses during prepatent infection, before egg deposition begins. CD4(+) T cells producing interleukin (IL)-4 were induced by both male and female worms during single-sex infections, demonstrating that this response is independent of exposure to eggs. The Th2 response was accompanied by production of immunoglobulin E and the sensitization of circulating basophils to produce additional IL-4 in response to schistosome antigens. Together, our data show that schistosome worms establish an immunologic milieu where CD4(+) T cells and basophils are both primed to produce IL-4 before eggs are laid, suggesting that worms play a role in establishment of the Th2 response that is critical for host survival and parasite transmission.
authors.affiliation: Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.
authors.forename: Lucia Alves
authors.initials: LA
authors.lastname: de Oliveira Fraga
authors.forename: Marina N
authors.initials: MN
authors.lastname: Torrero
authors.forename: Anna S
authors.initials: AS
authors.lastname: Tocheva
authors.forename: Edward
authors.initials: E
authors.lastname: Mitre
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Davies
mesh_terms: D000818:Animals; D000947:Antigens, Helminth; D001491:Basophils / Q000502:physiology; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D005260:Female; D005802:Genes, MHC Class II / Q000235:genetics*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D015847:Interleukin-4 / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010063:Ovum / Q000276:immunology; D012550:Schistosoma mansoni / Q000502:physiology*; D012555:Schistosomiasis mansoni / Q000276:immunology*
chemical_list: D000947:Antigens, Helminth; D015847:Interleukin-4; D007073:Immunoglobulin E