title: Ixodes ricinus tick salivary gland extract inhibits IL-10 secretion and CD69 expression by mitogen-stimulated murine splenocytes and induces hyporesponsiveness in B lymphocytes.
abstract: Tick saliva contains immunosuppressive factors allowing this blood-feeding ectoparasite to remain on hosts and enhancing pathogen transmission. In this study, we examined the modulation of mitogen-induced activation of naive murine splenocytes by the saliva and salivary gland extract (SGE) of I. ricinus ticks. We found that saliva-specific factors reduced IL-10 production by both concanavalin A (ConA) and lipopolysaccharide (LPS) stimulated splenocytes. The LPS-induced IL-10 production is 10 times more sensitive to SGE than the ConA-induced IL-10 production. Flow cytometric analysis determined that SGE particularly inhibited B (B220+) cell IL-10 production in mitogen-stimulated splenocyte preparations. Moreover, SGE reduced the early activation marker CD69 expression on ConA-activated T cells and also on B cells in presence of ConA or LPS. Annexin V and Via-probe staining demonstrated that SGE did not increase cell death in activated splenocytes and slightly decreased apoptosis in B lymphocytes. By employing assays with isolated B cells, we further showed that SGE had a direct effect on B cells and inhibited LPS-induced B cell proliferation. Taken together, our results indicate that salivary immunomodulators induce hyporesponsiveness to mitogen in both T and B cells, and that a direct B-cell inhibitory activity is present in tick saliva.
authors.affiliation: School of Biological Science (Zoology), University of Aberdeen, Aberdeen AB24 2TZ, Scotland, UK.
authors.forename: Sigrid
authors.initials: S
authors.lastname: Hannier
authors.forename: Janet
authors.initials: J
authors.lastname: Liversidge
authors.forename: Jerry M
authors.initials: JM
authors.lastname: Sternberg
authors.forename: Alan S
authors.initials: AS
authors.lastname: Bowman
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000032:analysis / Q000378:metabolism*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology*; D002457:Cell Extracts / Q000494:pharmacology; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D016753:Interleukin-10 / Q000032:analysis / Q000096:biosynthesis* / Q000378:metabolism; D018884:Ixodes / Q000737:chemistry*; D037181:Lectins, C-Type; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D012469:Salivary Glands / Q000737:chemistry; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D013601:T-Lymphocytes / Q000378:metabolism; D013997:Time Factors; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D002457:Cell Extracts; D003208:Concanavalin A; D016753:Interleukin-10; D037181:Lectins, C-Type; D008070:Lipopolysaccharides; D000099192:CD69 Antigens