title: Anopheles mosquito bites activate cutaneous mast cells leading to a local inflammatory response and lymph node hyperplasia.
abstract: When Anopheles mosquitoes probe the skin for blood feeding, they inject saliva in dermal tissue. Mosquito saliva is known to exert various biological activities, but its perception by the immune system and its role in parasite transmission remain poorly understood. In the present study, we report on the cellular changes occurring in the mouse skin and draining lymph nodes after a Anopheles stephensi mosquito bite. We show that mosquito bites induce dermal mast cell degranulation, leading to fluid extravasation and neutrophil influx. This inflammatory response does not occur in mast cell-deficient W/W(v) mice, unless these are reconstituted specifically with mast cells. Mast cell activation caused by A. stephensi mosquito bites is followed by hyperplasia of the draining lymph node due to the accumulation of CD3(+), B220(+), CD11b(+), and CD11c(+) leukocytes. The T cell enrichment of the draining lymph nodes results from their sequestration from the circulation rather than local proliferation. These data demonstrate that mosquito bites and very likely saliva rapidly trigger the immune system, emphasizing the critical contribution of peripheral mast cells in inducing T cell and dendritic cell recruitment within draining lymph nodes, a prerequisite for the elicitation of T and B lymphocyte priming.
authors.affiliation: Unités Immuno-Allergie, Institut Pasteur, Paris, France.
authors.forename: Christian E
authors.initials: CE
authors.lastname: Demeure
authors.forename: Karima
authors.initials: K
authors.lastname: Brahimi
authors.forename: Feriel
authors.initials: F
authors.lastname: Hacini
authors.forename: Françoise
authors.initials: F
authors.lastname: Marchand
authors.forename: Roger
authors.initials: R
authors.lastname: Péronet
authors.forename: Michel
authors.initials: M
authors.lastname: Huerre
authors.forename: Pierre
authors.initials: P
authors.lastname: St-Mezard
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Nicolas
authors.forename: Paul
authors.initials: P
authors.lastname: Brey
authors.forename: Guy
authors.initials: G
authors.lastname: Delespesse
authors.forename: Salaheddine
authors.initials: S
authors.lastname: Mécheri
mesh_terms: D000818:Animals; D000852:Anopheles / Q000472:pathogenicity*; D015550:Cell Degranulation; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D005260:Female; D006965:Hyperplasia / Q000209:etiology*; D007249:Inflammation / Q000209:etiology* / Q000473:pathology; D007299:Insect Bites and Stings / Q000276:immunology / Q000473:pathology*; D008198:Lymph Nodes / Q000473:pathology*; D008407:Mast Cells / Q000473:pathology*; D051379:Mice; D008815:Mice, Inbred Strains; D009504:Neutrophils / Q000502:physiology; D012463:Saliva / Q000276:immunology; D012867:Skin / Q000473:pathology; D013601:T-Lymphocytes / Q000502:physiology