NK cells are necessary for recovery of corneal CD11c+ dendritic cells after epithelial abrasion injury.

Mechanisms controlling CD11c(+) MHCII(+) DCs during corneal epithelial wound healing were investigated in a murine model of corneal abrasion. Selective depletion of NKp46(+) CD3- NK cells that normally migrate into the cornea after epithelial abrasion resulted in >85% reduction of the epithelial CD11c(+) MHCII(+) DCs, normally present during and after epithelial wound closure. Transfer (i.v.) of spleen NK cells into NK cell-depleted mice significantly restored levels of corneal epithelial DCs (P<0.01). Immigrated NK cells were predominately positive for IFN-γ, and topical corneal anti-IFN-γ reduced epithelial DCs by 79% (P<0.01). IFN-γ(-/-) mice had 69% fewer DCs than WT controls (P<0.01), and topical rIFN-γ applied to NK cell-depleted corneas increased epithelial DCs significantly (P<0.01). The contribution of ICAM-1, an adhesion molecule involved in leukocyte migration, expressed on healing corneal epithelium, was evaluated. ICAM-1(-/-) mice exhibited >70% reduction in epithelial DC recovery in the first 48 h after epithelial abrasion (P<0.01). These interventions reveal an early turnover of DCs in the epithelium after injury, and ICAM-1, NK cells, and IFN-γ are necessary for the immigration phase of this turnover.