title: Invariant NKT cells sustain specific B cell responses and memory.
abstract: Invariant natural killer T (iNKT) cells are innate-like lymphocytes recognizing CD1d-restricted glycolipid antigens, such as alpha-galactosylceramide (alphaGC). We assessed whether iNKT cells help B lymphocyte responses and found that mice immunized with proteins and alphaGC develop antibody titers 1-2 logs higher than those induced by proteins alone. Activation of iNKT cells enhances protection against infections such as influenza and elicits higher frequencies of memory B cells and higher antibody responses to booster immunizations. Protein vaccination with alphaGC, but not with conventional adjuvants, elicits IgG responses in mice lacking MHC class II molecules, demonstrating that iNKT cells can substitute for CD4(+) T cell help to B cells. Interestingly, the decay of circulating antibodies is faster in mice lacking iNKT cells. These findings point to a homeostatic role for iNKT cells on critical features of the antibody response such as immunity and B cell memory.
authors.affiliation: Novartis Vaccines, Via Fiorentina 1, 53100 Siena, Italy.
authors.forename: Grazia
authors.initials: G
authors.lastname: Galli
authors.forename: Paola
authors.initials: P
authors.lastname: Pittoni
authors.forename: Elena
authors.initials: E
authors.lastname: Tonti
authors.forename: Carmine
authors.initials: C
authors.lastname: Malzone
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Uematsu
authors.forename: Marco
authors.initials: M
authors.lastname: Tortoli
authors.forename: Domenico
authors.initials: D
authors.lastname: Maione
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Volpini
authors.forename: Oretta
authors.initials: O
authors.lastname: Finco
authors.forename: Sandra
authors.initials: S
authors.lastname: Nuti
authors.forename: Simona
authors.initials: S
authors.lastname: Tavarini
authors.forename: Paolo
authors.initials: P
authors.lastname: Dellabona
authors.forename: Rino
authors.initials: R
authors.lastname: Rappuoli
authors.forename: Giulia
authors.initials: G
authors.lastname: Casorati
authors.forename: Sergio
authors.initials: S
authors.lastname: Abrignani
mesh_terms: D000818:Animals; D018949:Antigens, CD1 / Q000378:metabolism; D055610:Antigens, CD1d; D001402:B-Lymphocytes / Q000378:metabolism* / Q000821:virology; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D005699:Galactosylceramides / Q000378:metabolism; D007107:Immune System; D007156:Immunologic Memory; D007694:Killer Cells, Natural / Q000378:metabolism* / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009976:Orthomyxoviridae Infections / Q000276:immunology; D013997:Time Factors
chemical_list: D018949:Antigens, CD1; D055610:Antigens, CD1d; D005699:Galactosylceramides; C493154:alpha-galactosylceramide