CD1D and influenza: To address whether NKT cells would also induce B cell immunity after vaccination with viral antigens, we intranasally immunized wild-type and CD1d−/− mice with hemagglutinin (HA) trimmer from the PR8 influenza strain in the presence or absence of two different adjuvants: alpha-galactosylceramide (α-GalCer) or poly(I:C).