title: Delayed-type hypersensitivity to Phlebotomus papatasi sand fly bite: An adaptive response induced by the fly?
abstract: The saliva of bloodsucking arthropods contains a large array of pharmacologically active compounds that assist hematophagy. Arthropod saliva is also responsible for causing uncomfortable allergic responses in its vertebrate hosts. In this article, we investigate whether the sand fly Phlebotomus papatasi, known to produce a strong delayed-type hypersensitivity (DTH) in humans, could benefit from, and possibly adaptively induce, this response in their vertebrate hosts. In this study, we show that flies fed on humans to completion nearly twice as fast in DTH sites as compared with normal skin sites. DTH sites had significantly larger blood flow as measured by the laser Doppler method. Sand flies feeding at sites in mouse ears that had a DTH response also fed faster than at normal sites. We conclude that in the case of P. papatasi, and possibly other arthropods such as fleas and bed bugs, the strong saliva-induced DTH response may reflect an adaptation of the fly to manipulate host immunity for the insect's own advantage.
authors.affiliation: Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Building 4, Room 126, 4 Center Drive, MSC-425, Bethesda, MD 20892-0425, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Belkaid
authors.forename: J G
authors.initials: JG
authors.lastname: Valenzuela
authors.forename: S
authors.initials: S
authors.lastname: Kamhawi
authors.forename: E
authors.initials: E
authors.lastname: Rowton
authors.forename: D L
authors.initials: DL
authors.lastname: Sacks
authors.forename: J M
authors.initials: JM
authors.lastname: Ribeiro
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000209:etiology* / Q000503:physiopathology; D007299:Insect Bites and Stings / Q000276:immunology*; D007303:Insect Vectors; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010691:Phlebotomus / Q000502:physiology*; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply