Induction of type 2 responses by schistosome worms during prepatent infection.
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.
de Oliveira Fraga
Lucia Alves
LA
Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.
Torrero
Marina N
MN
Tocheva
Anna S
AS
Mitre
Edward
E
Davies
Stephen J
SJ
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*
D000947:Antigens, Helminth; D015847:Interleukin-4; D007073:Immunoglobulin E