Essential role of LFA-1 in activating Th2-like responses by alpha-galactosylceramide-activated NKT cells.

NKT cells produce large amounts of cytokines associated with both the Th1 (IFN-gamma) and Th2 (IL-4) responses following stimulation of their invariant Valpha14 Ag receptor. The role of adhesion molecules in the activation of NKT cells by the Valpha14 ligand alpha-galactosylceramide (alpha-GalCer) remains unclear. To address this issue, LFA-1-/- (CD11a-/-) mice were used to investigate IL-4 and IFN-gamma production by NKT cells following alpha-GalCer stimulation. Intriguingly, LFA-1-/- mice showed increased IL-4, IL-5, and IL-13 production and polarized Th2-type responses in response to alpha-GalCer in vitro and in vivo. Furthermore, the Th2-specific transcription factor GATA-3 was up-regulated in alpha-GalCer-activated NKT cells from LFA-1-/- mice. These results provide the first genetic evidence that the adhesion receptor LFA-1 has a crucial role in Th2-polarizing functions of NKT cells.