title: The mechanism of splenic invariant NKT cell activation dictates localization in vivo.
abstract: Invariant NKT (iNKT) cells are glycolipid-specific innate lymphocytes emerging as critical players in the immune response to diverse infections and disease. iNKT cells are activated through cognate interactions with lipid-loaded APCs, by Ag-independent cytokine-mediated signaling pathways, or a combination of both. Although each of these modes of iNKT cell activation plays an important role in directing the humoral and cell-mediated immune response, the spatio-temporal nature of these interactions and the cellular requirements for activation are largely undefined. Combining novel in situ confocal imaging of αGalactosylceramide-loaded CD1d tetramer labeling to localize the endogenous iNKT cell population with cytokine reporter mice, we reveal the choreography of early murine splenic iNKT cell activation across diverse settings of glycolipid immunization and systemic infection with Streptococcus pneumoniae. We find that iNKT cells consolidate in the marginal zone and require dendritic cells lining the splenic marginal zone for activation following administration of cognate glycolipids and during systemic infection but not following exogenous cytokine administration. Although further establishing the importance of cognate iNKT cell interactions with APCs, we also show that noncognate iNKT-dependent mechanisms are sufficient to mediate effector outcomes, such as STAT signaling and dendritic cell licensing throughout the splenic parenchyma. Collectively, these data provide new insight into how iNKT cells may serve as a natural adjuvant in facilitating adaptive immune responses, irrespective of their tissue localization.
authors.affiliation: Trudeau Institute, Saranac Lake, NY 12983, USA.
authors.forename: Irah L
authors.initials: IL
authors.lastname: King
authors.forename: Eyal
authors.initials: E
authors.lastname: Amiel
authors.forename: Mike
authors.initials: M
authors.lastname: Tighe
authors.forename: Katja
authors.initials: K
authors.lastname: Mohrs
authors.forename: Natacha
authors.initials: N
authors.lastname: Veerapen
authors.forename: Gurdyal
authors.initials: G
authors.lastname: Besra
authors.forename: Markus
authors.initials: M
authors.lastname: Mohrs
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Leadbetter
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D055610:Antigens, CD1d / Q000276:immunology; D002450:Cell Communication; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D005699:Galactosylceramides; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D055611:Natural Killer T-Cells / Q000276:immunology*; D011008:Pneumococcal Infections / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D013154:Spleen / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology*
chemical_list: D055610:Antigens, CD1d; C526877:CD1D protein, human; D016207:Cytokines; D005699:Galactosylceramides; C493154:alpha-galactosylceramide