CD1d-restricted IFN-γ-secreting NKT cells promote immune complex-induced acute lung injury by regulating macrophage-inflammatory protein-1α production and activation of macrophages and dendritic cells

Immune complex-induced acute lung injury (IC-ALI) has been implicated in various pulmonary disease states. However, the role of NKT cells in IC-ALI remains unknown. Therefore, we explored NKT cell functions in IC-ALI using chicken egg albumin and anti-chicken egg albumin IgG. The bronchoalveolar lavage fluid of CD1d^-/- and Ja18^-/- mice contained few Ly6G ⁺CD11b⁺ granulocytes, whereas levels in B6 mice were greater and were increased further by α-galactosyl ceramide. IFN-γ and MIP-1α production in the lungs was greater in B6 than CD1d ^-/- mice. Adoptive transfer of wild type (WT) but not IFN-γ-, MIP-1α-, or FcγR-deficient NKT cells into CD1d^-/- mice caused recruitment of inflammatory cells to the lungs. Moreover, adoptive transfer of IFN-γR-deficient NKT cells enhanced MIP-1α production and cell recruitment in the lungs of CD1d^-/- or CD1d^-/- IFN-g^-/- mice, but to a lesser extent than WT NKT cells. This suggests that IFN-γ-producing NKT cells enhance MIP-1α production in both an autocrine and a paracrine manner. IFN-γ-deficient NKT cells induced less IL-1β and TNF-α production by alveolar macrophages and dendritic cells in CD1d^-/- mice than did WT NKT cells. Taken together, these data suggest that CD1d-restricted IFN-γ-producing NKT cells promote IC-ALI by producing MIP-1α and enhancing proinflammatory cytokine production by alveolar macrophages and dendritic cells.